diff --git a/.travis.yml b/.travis.yml
index 19ed0fbedf5d..f522f58574bf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,10 +24,10 @@ jobs:
     - { stage: python3working, python: 3.6, env: TOXENV=assets }
     - { stage: python3working, python: 3.6, env: TOXENV=es }
     - { stage: python3working, python: 3.6, env: TOXENV=addons-versions-and-files }
+    - { stage: python3working, python: 3.6, env: TOXENV=devhub }
     - { stage: python3working, python: 3.6, env: TOXENV=reviewers-and-zadmin }
     - { stage: python3working, python: 3.6, env: TOXENV=accounts-users-and-ratings }
     - { stage: python3working, python: 3.6, env: TOXENV=main }
-    - { stage: python3, python: 3.6, env: TOXENV=devhub }
     - { stage: python3, python: 3.6, env: TOXENV=amo-lib-locales-and-signing }
 
 env:
diff --git a/src/olympia/addons/forms.py b/src/olympia/addons/forms.py
index 762a1b2a7279..da4fa93e4138 100644
--- a/src/olympia/addons/forms.py
+++ b/src/olympia/addons/forms.py
@@ -5,6 +5,7 @@
 from django.conf import settings
 from django.core.files.storage import default_storage as storage
 from django.forms.formsets import BaseFormSet, formset_factory
+from django.utils.encoding import force_text
 from django.utils.translation import ugettext, ugettext_lazy as _, ungettext
 
 import six
@@ -229,7 +230,7 @@ def clean_categories(self):
                 'You can have only {0} categories.',
                 max_cat).format(max_cat))
 
-        has_misc = filter(lambda x: x.misc, categories)
+        has_misc = list(filter(lambda x: x.misc, categories))
         if has_misc and total > 1:
             raise forms.ValidationError(ugettext(
                 'The miscellaneous category cannot be combined with '
@@ -292,7 +293,7 @@ def icons():
     dirs, files = storage.listdir(settings.ADDON_ICONS_DEFAULT_PATH)
     for fname in files:
         if b'32' in fname and b'default' not in fname:
-            icon_name = fname.split(b'-')[0]
+            icon_name = force_text(fname.split(b'-')[0])
             icons.append(('icon/%s' % icon_name, icon_name))
     return sorted(icons)
 
diff --git a/src/olympia/devhub/file_validation_annotations.py b/src/olympia/devhub/file_validation_annotations.py
index da97165ac0cc..c378f57fda4e 100644
--- a/src/olympia/devhub/file_validation_annotations.py
+++ b/src/olympia/devhub/file_validation_annotations.py
@@ -5,7 +5,6 @@
 from xml.parsers.expat import ExpatError
 
 from django.utils.translation import ugettext
-from django.utils.encoding import force_bytes
 
 from olympia import amo
 from olympia.lib.akismet.models import AkismetReport
@@ -123,10 +122,8 @@ def annotate_search_plugin_validation(results, file_path, channel):
         return
 
     try:
-        # Requires bytes because defusedxml fails to detect
-        # unicode strings as filenames.
-        # https://gist.github.com/EnTeQuAk/25f99701d8b123f7611acd6ce0d5840b
-        dom = minidom.parse(force_bytes(file_path))
+        with open(file_path, 'r') as file_obj:
+            dom = minidom.parse(file_obj)
     except DefusedXmlException:
         url = 'https://pypi.python.org/pypi/defusedxml/0.3#attack-vectors'
         insert_validation_message(
diff --git a/src/olympia/devhub/forms.py b/src/olympia/devhub/forms.py
index ad2d01142233..3f2b8793eba5 100644
--- a/src/olympia/devhub/forms.py
+++ b/src/olympia/devhub/forms.py
@@ -67,15 +67,15 @@ def clean(self):
         if any(self.errors):
             return
         # cleaned_data could be None if it's the empty extra form.
-        data = filter(None, [f.cleaned_data for f in self.forms
-                             if not f.cleaned_data.get('DELETE', False)])
+        data = list(filter(None, [f.cleaned_data for f in self.forms
+                                  if not f.cleaned_data.get('DELETE', False)]))
         if not any(d['role'] == amo.AUTHOR_ROLE_OWNER for d in data):
             raise forms.ValidationError(
                 ugettext('Must have at least one owner.'))
         if not any(d['listed'] for d in data):
             raise forms.ValidationError(
                 ugettext('At least one author must be listed.'))
-        users = [d['user'] for d in data]
+        users = [d['user'].id for d in data]
         if sorted(users) != sorted(set(users)):
             raise forms.ValidationError(
                 ugettext('An author can only be listed once.'))
@@ -313,7 +313,7 @@ def clean_source(self):
                             'Unsupported file type, please upload an archive '
                             'file {extensions}.'.format(
                                 extensions=valid_extensions_string)))
-            except (zipfile.BadZipfile, tarfile.ReadError, IOError):
+            except (zipfile.BadZipfile, tarfile.ReadError, IOError, EOFError):
                 raise forms.ValidationError(
                     ugettext('Invalid or broken archive.'))
         return source
@@ -420,9 +420,9 @@ def __init__(self, *args, **kwargs):
         self.fields['max'].queryset = qs.all()
 
     def clean(self):
-        min = self.cleaned_data.get('min')
-        max = self.cleaned_data.get('max')
-        if not (min and max and min.version_int <= max.version_int):
+        min_ = self.cleaned_data.get('min')
+        max_ = self.cleaned_data.get('max')
+        if not (min_ and max_ and min_.version_int <= max_.version_int):
             raise forms.ValidationError(ugettext('Invalid version range.'))
         return self.cleaned_data
 
@@ -465,8 +465,8 @@ def clean(self):
         if any(self.errors):
             return
 
-        apps = filter(None, [f.cleaned_data for f in self.forms
-                             if not f.cleaned_data.get('DELETE', False)])
+        apps = list(filter(None, [f.cleaned_data for f in self.forms
+                                  if not f.cleaned_data.get('DELETE', False)]))
 
         if not apps:
             # At this point, we're raising a global error and re-displaying the
@@ -653,7 +653,7 @@ def clean(self):
         super(CombinedNameSummaryCleanMixin, self).clean()
         name_summary_locales = set(
             list(self.cleaned_data.get('name', {}).keys()) +
-            self.cleaned_data.get('summary', {}).keys())
+            list(self.cleaned_data.get('summary', {}).keys()))
         default_locale = self.instance.default_locale.lower()
         name_values = self.cleaned_data.get('name') or {}
         name_default = name_values.get(default_locale) or ''
diff --git a/src/olympia/devhub/tasks.py b/src/olympia/devhub/tasks.py
index 0395565b017f..2f98c7e3e3b4 100644
--- a/src/olympia/devhub/tasks.py
+++ b/src/olympia/devhub/tasks.py
@@ -17,6 +17,7 @@
 from django.core.validators import ValidationError
 from django.db import transaction
 from django.template import loader
+from django.utils.encoding import force_text
 from django.utils.translation import ugettext
 
 import celery
@@ -161,7 +162,7 @@ def wrapper(task, akismet_results, id_or_path, **kwargs):
         task.ignore_result = True
         try:
             data = fn(id_or_path, **kwargs)
-            results = json.loads(data)
+            results = json.loads(force_text(data))
             if akismet_results:
                 annotations.annotate_akismet_spam_check(
                     results, akismet_results)
@@ -448,7 +449,7 @@ def run_addons_linter(path, channel):
     if error:
         raise ValueError(error)
 
-    parsed_data = json.loads(output)
+    parsed_data = json.loads(force_text(output))
 
     result = json.dumps(fix_addons_linter_output(parsed_data, channel))
     track_validation_stats(result)
@@ -460,7 +461,7 @@ def track_validation_stats(json_result):
     """
     Given a raw JSON string of validator results, log some stats.
     """
-    result = json.loads(json_result)
+    result = json.loads(force_text(json_result))
     result_kind = 'success' if result['errors'] == 0 else 'failure'
     statsd.incr('devhub.linter.results.all.{}'.format(result_kind))
 
diff --git a/src/olympia/devhub/templatetags/jinja_helpers.py b/src/olympia/devhub/templatetags/jinja_helpers.py
index afc63979f49f..950bb12208ce 100644
--- a/src/olympia/devhub/templatetags/jinja_helpers.py
+++ b/src/olympia/devhub/templatetags/jinja_helpers.py
@@ -1,5 +1,3 @@
-import urllib
-
 from collections import defaultdict
 
 from django.utils.encoding import force_bytes
@@ -9,6 +7,7 @@
 import six
 
 from django_jinja import library
+from six.moves.urllib.parse import unquote_to_bytes
 
 from olympia import amo
 from olympia.access import acl
@@ -120,7 +119,7 @@ def display_url(url):
     Note: returns a Unicode object, not a valid URL.
     """
     url = force_bytes(url, errors='replace')
-    return urllib.unquote(url).decode('utf-8', errors='replace')
+    return unquote_to_bytes(url).decode('utf-8', errors='replace')
 
 
 @library.global_function
diff --git a/src/olympia/devhub/tests/test_feeds.py b/src/olympia/devhub/tests/test_feeds.py
index 3999ef6001f5..06ce05005ce0 100644
--- a/src/olympia/devhub/tests/test_feeds.py
+++ b/src/olympia/devhub/tests/test_feeds.py
@@ -1,5 +1,7 @@
 import uuid
 
+from django.utils.encoding import force_text
+
 import six
 from six.moves.urllib_parse import urlencode
 
@@ -176,34 +178,35 @@ def test_filter_addon_otherguy(self):
     def test_rss(self):
         self.log_creates(5)
         # This will give us a new RssKey
-        r = self.get_response()
+        self.get_response()
         key = RssKey.objects.get()
 
         assert isinstance(key.key, uuid.UUID)
 
-        r = self.get_response(privaterss=key.key)
-        assert r['content-type'] == 'application/rss+xml; charset=utf-8'
-        assert '<title>Recent Changes for My Add-ons</title>' in r.content
+        res = self.get_response(privaterss=key.key)
+        assert res['content-type'] == 'application/rss+xml; charset=utf-8'
+        assert b'<title>Recent Changes for My Add-ons</title>' in res.content
 
     def test_rss_accepts_verbose(self):
         self.log_creates(5)
-        r = self.get_response()
+        self.get_response()
         key = RssKey.objects.get()
-        r = self.get_response(privaterss=str(key.key))
-        assert r['content-type'] == 'application/rss+xml; charset=utf-8'
-        assert '<title>Recent Changes for My Add-ons</title>' in r.content
+        res = self.get_response(privaterss=str(key.key))
+        assert res['content-type'] == 'application/rss+xml; charset=utf-8'
+        assert b'<title>Recent Changes for My Add-ons</title>' in res.content
 
     def test_rss_single(self):
         self.log_creates(5)
         self.log_creates(13, self.addon2)
 
         # This will give us a new RssKey
-        r = self.get_response(addon=self.addon.id)
+        self.get_response(addon=self.addon.id)
         key = RssKey.objects.get()
-        r = self.get_response(privaterss=key.key)
-        assert r['content-type'] == 'application/rss+xml; charset=utf-8'
-        assert len(pq(r.content)('item')) == 5
-        assert '<title>Recent Changes for %s</title>' % self.addon in r.content
+        res = self.get_response(privaterss=key.key)
+        assert res['content-type'] == 'application/rss+xml; charset=utf-8'
+        assert len(pq(res.content)('item')) == 5
+        assert '<title>Recent Changes for %s</title>' % self.addon in (
+            force_text(res.content))
 
     def test_rss_unlisted_addon(self):
         """Unlisted addon logs appear in the rss feed."""
@@ -293,11 +296,11 @@ def test_hidden(self):
         res = self.get_response(addon=self.addon.id)
         key = RssKey.objects.get()
         res = self.get_response(privaterss=key.key)
-        assert "<title>Comment on" not in res.content
+        assert b'<title>Comment on' not in res.content
 
     def test_no_guid(self):
         self.log_creates(1)
         self.get_response(addon=self.addon.id)
         key = RssKey.objects.get()
         res = self.get_response(privaterss=key.key)
-        assert "<guid>" not in res.content
+        assert b'<guid>' not in res.content
diff --git a/src/olympia/devhub/tests/test_forms.py b/src/olympia/devhub/tests/test_forms.py
index c2a08c4f14e9..c85790390335 100644
--- a/src/olympia/devhub/tests/test_forms.py
+++ b/src/olympia/devhub/tests/test_forms.py
@@ -6,6 +6,7 @@
 from django.conf import settings
 from django.core.files.storage import default_storage as storage
 from django.utils import translation
+from django.utils.encoding import force_text
 
 import mock
 import pytest
@@ -255,8 +256,8 @@ def test_preview_modified(self, update_mock):
         name = 'transparent.png'
         form = forms.PreviewForm({'caption': 'test', 'upload_hash': name,
                                   'position': 1})
-        with storage.open(os.path.join(self.dest, name), 'w') as f:
-            shutil.copyfileobj(open(get_image_path(name)), f)
+        with storage.open(os.path.join(self.dest, name), 'wb') as f:
+            shutil.copyfileobj(open(get_image_path(name), 'rb'), f)
         assert form.is_valid()
         form.save(addon)
         assert update_mock.called
@@ -267,8 +268,8 @@ def test_preview_size(self, pngcrush_image_mock):
         name = 'teamaddons.jpg'
         form = forms.PreviewForm({'caption': 'test', 'upload_hash': name,
                                   'position': 1})
-        with storage.open(os.path.join(self.dest, name), 'w') as f:
-            shutil.copyfileobj(open(get_image_path(name)), f)
+        with storage.open(os.path.join(self.dest, name), 'wb') as f:
+            shutil.copyfileobj(open(get_image_path(name), 'rb'), f)
         assert form.is_valid()
         form.save(addon)
         preview = addon.previews.all()[0]
@@ -433,7 +434,8 @@ def test_success(self, save_persona_image_mock,
         # Upload header image.
         img = open(get_image_path('persona-header.jpg'), 'rb')
         r_ajax = self.client.post(header_url, {'upload_image': img})
-        data.update(header_hash=json.loads(r_ajax.content)['upload_hash'])
+        content = json.loads(force_text(r_ajax.content))
+        data.update(header_hash=content['upload_hash'])
 
         # Populate and save form.
         self.post()
diff --git a/src/olympia/devhub/tests/test_helpers.py b/src/olympia/devhub/tests/test_helpers.py
index e0e57cd1c96d..e76699d796fd 100644
--- a/src/olympia/devhub/tests/test_helpers.py
+++ b/src/olympia/devhub/tests/test_helpers.py
@@ -1,12 +1,12 @@
 # -*- coding: utf-8 -*-
-import urllib
-
 from django.utils import translation
+from django.utils.encoding import force_bytes, force_text
 
 import pytest
 import six
 
 from mock import Mock
+from six.moves.urllib.parse import quote
 
 from olympia import amo
 from olympia.activity.models import ActivityLog
@@ -72,17 +72,17 @@ class TestDisplayUrl(amo.tests.BaseTestCase):
 
     def setUp(self):
         super(TestDisplayUrl, self).setUp()
-        self.raw_url = u'http://host/%s' % 'フォクすけといっしょ'.decode('utf8')
+        self.raw_url = u'http://host/%s' % u'フォクすけといっしょ'
 
     def test_utf8(self):
-        url = urllib.quote(self.raw_url.encode('utf8'))
-        assert render('{{ url|display_url }}', {'url': url}) == (
+        url = quote(self.raw_url.encode('utf8'))
+        assert render(u'{{ url|display_url }}', {'url': url}) == (
             self.raw_url)
 
     def test_unicode(self):
-        url = urllib.quote(self.raw_url.encode('utf8'))
-        url = six.text_type(url, 'utf8')
-        assert render('{{ url|display_url }}', {'url': url}) == (
+        url = quote(self.raw_url.encode('utf8'))
+        url = force_text(force_bytes(url, 'utf8'), 'utf8')
+        assert render(u'{{ url|display_url }}', {'url': url}) == (
             self.raw_url)
 
 
diff --git a/src/olympia/devhub/tests/test_tasks.py b/src/olympia/devhub/tests/test_tasks.py
index 97dc5a5a314a..f670671d4583 100644
--- a/src/olympia/devhub/tests/test_tasks.py
+++ b/src/olympia/devhub/tests/test_tasks.py
@@ -75,7 +75,7 @@ def _uploader(resize_size, final_size):
     original_size = (339, 128)
 
     src = tempfile.NamedTemporaryFile(
-        mode='r+w+b', suffix='.png', delete=False, dir=settings.TMP_PATH)
+        mode='r+b', suffix='.png', delete=False, dir=settings.TMP_PATH)
 
     if not isinstance(final_size, list):
         final_size = [final_size]
@@ -122,18 +122,20 @@ def test_recreate_previews(pngcrush_image_mock):
     addon = addon_factory()
     # Set up the preview so it has files in the right places.
     preview_no_original = Preview.objects.create(addon=addon)
-    with storage.open(preview_no_original.image_path, 'w') as dest:
-        shutil.copyfileobj(open(get_image_path('preview_landscape.jpg')), dest)
-    with storage.open(preview_no_original.thumbnail_path, 'w') as dest:
-        shutil.copyfileobj(open(get_image_path('mozilla.png')), dest)
+    with storage.open(preview_no_original.image_path, 'wb') as dest:
+        shutil.copyfileobj(open(get_image_path('preview_landscape.jpg'), 'rb'),
+                           dest)
+    with storage.open(preview_no_original.thumbnail_path, 'wb') as dest:
+        shutil.copyfileobj(open(get_image_path('mozilla.png'), 'rb'), dest)
     # And again but this time with an "original" image.
     preview_has_original = Preview.objects.create(addon=addon)
-    with storage.open(preview_has_original.image_path, 'w') as dest:
-        shutil.copyfileobj(open(get_image_path('preview_landscape.jpg')), dest)
-    with storage.open(preview_has_original.thumbnail_path, 'w') as dest:
-        shutil.copyfileobj(open(get_image_path('mozilla.png')), dest)
-    with storage.open(preview_has_original.original_path, 'w') as dest:
-        shutil.copyfileobj(open(get_image_path('teamaddons.jpg')), dest)
+    with storage.open(preview_has_original.image_path, 'wb') as dest:
+        shutil.copyfileobj(open(get_image_path('preview_landscape.jpg'), 'rb'),
+                           dest)
+    with storage.open(preview_has_original.thumbnail_path, 'wb') as dest:
+        shutil.copyfileobj(open(get_image_path('mozilla.png'), 'rb'), dest)
+    with storage.open(preview_has_original.original_path, 'wb') as dest:
+        shutil.copyfileobj(open(get_image_path('teamaddons.jpg'), 'rb'), dest)
 
     tasks.recreate_previews([addon.id])
 
diff --git a/src/olympia/devhub/tests/test_views.py b/src/olympia/devhub/tests/test_views.py
index 6188b95a23b8..2b64da57d60c 100644
--- a/src/olympia/devhub/tests/test_views.py
+++ b/src/olympia/devhub/tests/test_views.py
@@ -9,6 +9,7 @@
 from django.core.files.storage import default_storage as storage
 from django.test import RequestFactory
 from django.test.utils import override_settings
+from django.utils.encoding import force_text
 from django.utils.translation import trim_whitespace
 
 import mock
@@ -425,7 +426,7 @@ def test_counts(self):
                                   version=addon.current_version)
 
         url = reverse('devhub.versions.stats', args=[addon.slug])
-        data = json.loads(self.client.get(url).content)
+        data = json.loads(force_text(self.client.get(url).content))
         exp = {str(version.id):
                {'reviews': 10, 'files': 1, 'version': version.version,
                 'id': version.id}}
@@ -531,7 +532,7 @@ def test_basic_logged_out(self):
         response = self.client.get(self.url)
         assert response.status_code == 200
         self.assertTemplateUsed(response, 'devhub/index.html')
-        assert 'Customize Firefox' in response.content
+        assert b'Customize Firefox' in response.content
 
     def test_default_lang_selected(self):
         self.client.logout()
@@ -543,7 +544,7 @@ def test_basic_logged_in(self):
         response = self.client.get(self.url)
         assert response.status_code == 200
         self.assertTemplateUsed(response, 'devhub/index.html')
-        assert 'My Add-ons' in response.content
+        assert b'My Add-ons' in response.content
 
     def test_my_addons_addon_versions_link(self):
         assert self.client.login(email='del@icio.us')
@@ -953,7 +954,7 @@ def test_detail_json(self):
         response = self.client.get(reverse('devhub.upload_detail',
                                    args=[upload.uuid.hex, 'json']))
         assert response.status_code == 200
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
 
         assert data['validation']['errors'] == 1
         assert data['url'] == (
@@ -1042,7 +1043,7 @@ def test_no_servererror_on_missing_version(self):
         upload = FileUpload.objects.get()
         response = self.client.get(
             reverse('devhub.upload_detail', args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         message = [(m['message'], m.get('type') == 'error')
                    for m in data['validation']['messages']]
         expected = [(u'&#34;/version&#34; is a required property', True)]
@@ -1057,7 +1058,7 @@ def test_unparsable_xpi(self, flag_is_active, v):
         upload = FileUpload.objects.get()
         response = self.client.get(
             reverse('devhub.upload_detail', args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         message = [(m['message'], m.get('fatal', False))
                    for m in data['validation']['messages']]
         assert message == [
@@ -1074,7 +1075,7 @@ def test_experiment_xpi_allowed(self, mock_validator):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'] == []
 
     @mock.patch('olympia.devhub.tasks.run_addons_linter')
@@ -1085,7 +1086,7 @@ def test_experiment_xpi_not_allowed(self, mock_validator):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'] == [
             {u'tier': 1, u'message': u'You cannot submit this type of add-on',
              u'fatal': True, u'type': u'error'}]
@@ -1100,7 +1101,7 @@ def test_system_addon_allowed(self, mock_validator):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'] == []
 
     @mock.patch('olympia.devhub.tasks.run_addons_linter')
@@ -1113,7 +1114,7 @@ def test_system_addon_not_allowed_not_mozilla(self, mock_validator):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'] == [
             {u'tier': 1,
              u'message': u'You cannot submit an add-on with a guid ending '
@@ -1133,7 +1134,7 @@ def test_mozilla_signed_allowed(self, mock_get_signature, mock_validator):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'] == []
 
     @mock.patch('olympia.files.utils.get_signer_organizational_unit_name')
@@ -1146,7 +1147,7 @@ def test_mozilla_signed_not_allowed_not_mozilla(self, mock_get_signature):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'] == [
             {u'tier': 1,
              u'message': u'You cannot submit a Mozilla Signed Extension',
@@ -1172,7 +1173,7 @@ def test_legacy_mozilla_signed_fx57_compat_allowed(self):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
 
         msg = data['validation']['messages'][0]
 
@@ -1195,7 +1196,7 @@ def test_system_addon_update_allowed(self, mock_validator):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail_for_version',
                                            args=[addon.slug, upload.uuid.hex]))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'] == []
 
     def test_legacy_langpacks_disallowed(self):
@@ -1204,7 +1205,7 @@ def test_legacy_langpacks_disallowed(self):
         upload = FileUpload.objects.get()
         response = self.client.get(reverse('devhub.upload_detail',
                                            args=[upload.uuid.hex, 'json']))
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'][0]['id'] == [
             u'validation', u'messages', u'legacy_addons_unsupported'
         ]
@@ -1246,7 +1247,7 @@ def test_akismet_reports_created_ham_outcome(self, comment_check_mock):
         report = AkismetReport.objects.get(upload_instance=upload)
         assert report.comment_type == 'product-name'
         assert report.comment == 'Beastify'  # the addon's name
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
     @override_switch('akismet-spam-check', active=True)
     @override_switch('akismet-addon-action', active=False)
@@ -1266,7 +1267,7 @@ def test_akismet_reports_created_spam_outcome_logging_only(self):
         assert report.comment_type == 'product-name'
         assert report.comment == 'Beastify'  # the addon's name
         assert report.result == AkismetReport.MAYBE_SPAM
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
     @override_switch('akismet-spam-check', active=True)
     @override_switch('akismet-addon-action', active=True)
@@ -1285,9 +1286,9 @@ def test_akismet_reports_created_spam_outcome_action_taken(self):
         report = AkismetReport.objects.get(upload_instance=upload)
         assert report.comment_type == 'product-name'
         assert report.comment == 'Beastify'  # the addon's name
-        assert 'spam' in response.content
+        assert b'spam' in response.content
         assert report.result == AkismetReport.MAYBE_SPAM
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data['validation']['messages'][0]['id'] == [
             u'validation', u'messages', u'akismet_is_spam_name'
         ]
@@ -1317,7 +1318,7 @@ def test_akismet_reports_created_l10n(self, comment_check_mock):
             u'Varsling ved trykk på lenke i18n',  # nb_NO
         ]
         assert report.comment in names
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
     @override_switch('akismet-spam-check', active=True)
     def test_akismet_reports_not_created_for_unlisted(self):
@@ -1446,8 +1447,8 @@ def test_unique_version_num(self):
             version='<script>alert("Happy XSS-Xmas");<script>')
         response = self.client.get(reverse('devhub.addons'))
         assert response.status_code == 200
-        assert '<script>alert' not in response.content
-        assert '&lt;script&gt;alert' in response.content
+        assert b'<script>alert' not in response.content
+        assert b'&lt;script&gt;alert' in response.content
 
 
 class TestDeleteAddon(TestCase):
@@ -1740,7 +1741,7 @@ def test_wrong_user(self):
     def test_no_header_image(self):
         response = self.client.post(self.url, follow=True)
         assert response.status_code == 200
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data == {}
 
     def test_header_image(self):
@@ -1750,7 +1751,7 @@ def test_header_image(self):
         copy_stored_file(zip_file, destination)
         response = self.client.post(self.url, follow=True)
         assert response.status_code == 200
-        data = json.loads(response.content)
+        data = json.loads(force_text(response.content))
         assert data
         assert len(data.items()) == 1
         assert 'weta.png' in data
diff --git a/src/olympia/devhub/tests/test_views_edit.py b/src/olympia/devhub/tests/test_views_edit.py
index 7eca7d377232..7d96649af5e8 100644
--- a/src/olympia/devhub/tests/test_views_edit.py
+++ b/src/olympia/devhub/tests/test_views_edit.py
@@ -4,6 +4,7 @@
 
 from django.core.cache import cache
 from django.core.files.storage import default_storage as storage
+from django.utils.encoding import force_text
 
 import mock
 import six
@@ -345,7 +346,7 @@ def test_akismet_edit_is_ham(self, comment_check_mock):
         assert description_report.comment == data['description']
 
         assert comment_check_mock.call_count == 3
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
         # And metadata was updated
         addon = self.get_addon()
@@ -377,7 +378,7 @@ def test_akismet_edit_is_spam_logging_only(self, comment_check_mock):
 
         assert comment_check_mock.call_count == 3
         # But because we're not taking any action from the spam, don't report.
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
         # And metadata was updated
         addon = self.get_addon()
@@ -446,9 +447,9 @@ def test_edit_xss(self):
         response = self.client.get(self.describe_edit_url)
         assert response.status_code == 200
 
-        assert '<script>' not in response.content
-        assert ('This\n&lt;b&gt;IS&lt;/b&gt;&lt;script&gt;alert(&#39;awesome'
-                '&#39;)&lt;/script&gt;</textarea>') in response.content
+        assert b'<script>' not in response.content
+        assert (b'This\n&lt;b&gt;IS&lt;/b&gt;&lt;script&gt;alert(&#39;awesome'
+                b'&#39;)&lt;/script&gt;</textarea>') in response.content
 
     def test_description_optional(self):
         """Description is optional by default - so confirm that here and
@@ -472,8 +473,8 @@ def test_description_min_length_not_in_html_attrs(self):
     def test_name_summary_lengths_short(self):
         # check the separate name and summary labels, etc are served
         response = self.client.get(self.url)
-        assert 'Name and Summary' not in response.content
-        assert 'It will be shown in listings and searches' in response.content
+        assert b'Name and Summary' not in response.content
+        assert b'It will be shown in listings and searches' in response.content
 
         self.client.post(
             self.describe_edit_url, self.get_dict(name='a', summary='b'))
@@ -492,7 +493,7 @@ def test_name_summary_lengths_long(self):
     def test_name_summary_lengths_content_optimization(self):
         # check the combined name and summary label, etc are served
         response = self.client.get(self.url)
-        assert 'Name and Summary' in response.content
+        assert b'Name and Summary' in response.content
 
         # name and summary are too short
         response = self.client.post(
@@ -625,8 +626,9 @@ def test_edit_no_previous_categories(self):
 
         # Make sure the categories list we display to the user in the response
         # has been updated.
-        assert set(response.context['addon'].all_categories) == set(
-            self.addon.all_categories)
+        assert (
+            set(cat.id for cat in response.context['addon'].all_categories) ==
+            set(cat.id for cat in self.addon.all_categories))
 
     def test_edit_categories_addandremove(self):
         AddonCategory(addon=self.addon, category_id=1).save()
@@ -641,8 +643,9 @@ def test_edit_categories_addandremove(self):
 
         # Make sure the categories list we display to the user in the response
         # has been updated.
-        assert set(response.context['addon'].all_categories) == set(
-            self.addon.all_categories)
+        assert (
+            set(cat.id for cat in response.context['addon'].all_categories) ==
+            set(cat.id for cat in self.addon.all_categories))
 
     def test_edit_categories_remove(self):
         category = Category.objects.get(id=1)
@@ -659,7 +662,7 @@ def test_edit_categories_remove(self):
 
         # Make sure the categories list we display to the user in the response
         # has been updated.
-        assert set(response.context['addon'].all_categories) == set(
+        assert response.context['addon'].all_categories == (
             self.addon.all_categories)
 
     def test_edit_categories_required(self):
@@ -928,7 +931,7 @@ def test_edit_media_uploadedicon(self):
         data = {'upload_image': src_image}
 
         response = self.client.post(self.icon_upload, data)
-        response_json = json.loads(response.content)
+        response_json = json.loads(force_text(response.content))
         addon = self.get_addon()
 
         # Now, save the form so it gets moved properly.
@@ -951,7 +954,7 @@ def test_edit_media_uploadedicon(self):
 
         # Check that it was actually uploaded
         dirname = os.path.join(user_media_path('addon_icons'),
-                               '%s' % (addon.id / 1000))
+                               '%s' % (addon.id // 1000))
         dest = os.path.join(dirname, '%s-32.png' % addon.id)
 
         assert storage.exists(dest)
@@ -974,7 +977,7 @@ def test_edit_media_uploadedicon_noresize(self):
         data = {'upload_image': src_image}
 
         response = self.client.post(self.icon_upload, data)
-        response_json = json.loads(response.content)
+        response_json = json.loads(force_text(response.content))
         addon = self.get_addon()
 
         # Now, save the form so it gets moved properly.
@@ -997,7 +1000,7 @@ def test_edit_media_uploadedicon_noresize(self):
 
         # Check that it was actually uploaded
         dirname = os.path.join(user_media_path('addon_icons'),
-                               '%s' % (addon.id / 1000))
+                               '%s' % (addon.id // 1000))
         dest = os.path.join(dirname, '%s-64.png' % addon.id)
 
         assert storage.exists(dest)
@@ -1012,7 +1015,7 @@ def check_image_type(self, url, msg):
         src_image = open(img, 'rb')
 
         res = self.client.post(url, {'upload_image': src_image})
-        response_json = json.loads(res.content)
+        response_json = json.loads(force_text(res.content))
         assert response_json['errors'][0] == msg
 
     def test_edit_media_icon_wrong_type(self):
@@ -1042,55 +1045,55 @@ def test_image_status_no_choice(self):
         addon = self.get_addon()
         addon.update(icon_type='')
         url = reverse('devhub.ajax.image.status', args=[addon.slug])
-        result = json.loads(self.client.get(url).content)
+        result = json.loads(force_text(self.client.get(url).content))
         assert result['icons']
 
     def test_image_status_works(self):
         self.setup_image_status()
-        result = json.loads(self.client.get(self.url).content)
+        result = json.loads(force_text(self.client.get(self.url).content))
         assert result['icons']
 
     def test_image_status_fails(self):
         self.setup_image_status()
         storage.delete(self.icon_dest)
-        result = json.loads(self.client.get(self.url).content)
+        result = json.loads(force_text(self.client.get(self.url).content))
         assert not result['icons']
 
     def test_preview_status_works(self):
         self.setup_image_status()
-        result = json.loads(self.client.get(self.url).content)
+        result = json.loads(force_text(self.client.get(self.url).content))
         assert result['previews']
 
         # No previews means that all the images are done.
         self.addon.previews.all().delete()
-        result = json.loads(self.client.get(self.url).content)
+        result = json.loads(force_text(self.client.get(self.url).content))
         assert result['previews']
 
     def test_preview_status_fails(self):
         self.setup_image_status()
         storage.delete(self.preview.thumbnail_path)
-        result = json.loads(self.client.get(self.url).content)
+        result = json.loads(force_text(self.client.get(self.url).content))
         assert not result['previews']
 
     def test_image_status_persona(self):
         self.setup_image_status()
         storage.delete(self.icon_dest)
         self.get_addon().update(type=amo.ADDON_PERSONA)
-        result = json.loads(self.client.get(self.url).content)
+        result = json.loads(force_text(self.client.get(self.url).content))
         assert result['icons']
 
     def test_image_status_default(self):
         self.setup_image_status()
         storage.delete(self.icon_dest)
         self.get_addon().update(icon_type='icon/photos')
-        result = json.loads(self.client.get(self.url).content)
+        result = json.loads(force_text(self.client.get(self.url).content))
         assert result['icons']
 
     def check_image_animated(self, url, msg):
         filehandle = open(get_image_path('animated.png'), 'rb')
 
         res = self.client.post(url, {'upload_image': filehandle})
-        response_json = json.loads(res.content)
+        response_json = json.loads(force_text(res.content))
         assert response_json['errors'][0] == msg
 
     def test_icon_animated(self):
@@ -1110,27 +1113,29 @@ def test_icon_dimensions_and_ratio(self):
         response = self.client.post(
             self.icon_upload,
             {'upload_image': open(get_image_path('mozilla-small.png'), 'rb')})
-        assert json.loads(response.content)['errors'] == [size_msg, ratio_msg]
+        assert json.loads(force_text(response.content))['errors'] == [
+            size_msg, ratio_msg]
 
         # icon64.png is the right ratio, but only 64x64
         response = self.client.post(
             self.icon_upload,
             {'upload_image': open(
                 get_image_path('icon64.png'), 'rb')})
-        assert json.loads(response.content)['errors'] == [size_msg]
+        assert json.loads(force_text(response.content))['errors'] == [size_msg]
 
         # mozilla.png is big enough but still not square
         response = self.client.post(
             self.icon_upload,
             {'upload_image': open(get_image_path('mozilla.png'), 'rb')})
-        assert json.loads(response.content)['errors'] == [ratio_msg]
+        assert json.loads(force_text(response.content))['errors'] == [
+            ratio_msg]
 
         # and mozilla-sq is the right ratio and big enough
         response = self.client.post(
             self.icon_upload,
             {'upload_image': open(get_image_path('mozilla-sq.png'), 'rb')})
-        assert json.loads(response.content)['errors'] == []
-        assert json.loads(response.content)['upload_hash']
+        assert json.loads(force_text(response.content))['errors'] == []
+        assert json.loads(force_text(response.content))['upload_hash']
 
     def preview_add(self, amount=1, image_name='preview_4x3.jpg'):
         src_image = open(get_image_path(image_name), 'rb')
@@ -1140,7 +1145,7 @@ def preview_add(self, amount=1, image_name='preview_4x3.jpg'):
         url = self.preview_upload
         response = self.client.post(url, data_formset)
 
-        details = json.loads(response.content)
+        details = json.loads(force_text(response.content))
         upload_hash = details['upload_hash']
 
         # Create and post with the formset.
@@ -1175,27 +1180,29 @@ def test_preview_dimensions_and_ratio(self):
         response = self.client.post(
             self.preview_upload,
             {'upload_image': open(get_image_path('mozilla.png'), 'rb')})
-        assert json.loads(response.content)['errors'] == [size_msg, ratio_msg]
+        assert json.loads(force_text(response.content))['errors'] == [
+            size_msg, ratio_msg]
 
         # preview_landscape.jpg is the right ratio-ish, but too small
         response = self.client.post(
             self.preview_upload,
             {'upload_image': open(
                 get_image_path('preview_landscape.jpg'), 'rb')})
-        assert json.loads(response.content)['errors'] == [size_msg]
+        assert json.loads(force_text(response.content))['errors'] == [size_msg]
 
         # teamaddons.jpg is big enough but still wrong ratio.
         response = self.client.post(
             self.preview_upload,
             {'upload_image': open(get_image_path('teamaddons.jpg'), 'rb')})
-        assert json.loads(response.content)['errors'] == [ratio_msg]
+        assert json.loads(force_text(response.content))['errors'] == [
+            ratio_msg]
 
         # and preview_4x3.jpg is the right ratio and big enough
         response = self.client.post(
             self.preview_upload,
             {'upload_image': open(get_image_path('preview_4x3.jpg'), 'rb')})
-        assert json.loads(response.content)['errors'] == []
-        assert json.loads(response.content)['upload_hash']
+        assert json.loads(force_text(response.content))['errors'] == []
+        assert json.loads(force_text(response.content))['upload_hash']
 
     def test_edit_media_preview_edit(self):
         self.preview_add()
@@ -1657,7 +1664,7 @@ def test_edit_categories_set(self):
         assert [cat.id for cat in self.get_addon().all_categories] == []
         response = self.client.post(
             self.describe_edit_url, self.get_dict(category='firefox'))
-        assert set(response.context['addon'].all_categories) == set(
+        assert response.context['addon'].all_categories == (
             self.get_addon().all_categories)
 
         addon_cats = self.get_addon().categories.values_list('id', flat=True)
diff --git a/src/olympia/devhub/tests/test_views_submit.py b/src/olympia/devhub/tests/test_views_submit.py
index 048f30af3903..e1c7eb34ba58 100644
--- a/src/olympia/devhub/tests/test_views_submit.py
+++ b/src/olympia/devhub/tests/test_views_submit.py
@@ -106,7 +106,7 @@ def get_addon(self):
     def get_version(self):
         return self.get_addon().versions.latest()
 
-    def generate_source_zip(self, suffix='.zip', data='z' * (2 ** 21),
+    def generate_source_zip(self, suffix='.zip', data=u'z' * (2 ** 21),
                             compression=zipfile.ZIP_DEFLATED):
         tdir = temp.gettempdir()
         source = temp.NamedTemporaryFile(suffix=suffix, dir=tdir)
@@ -116,7 +116,7 @@ def generate_source_zip(self, suffix='.zip', data='z' * (2 ** 21),
         return source
 
     def generate_source_tar(
-            self, suffix='.tar.gz', data='t' * (2 ** 21), mode=None):
+            self, suffix='.tar.gz', data=b't' * (2 ** 21), mode=None):
         tdir = temp.gettempdir()
         source = temp.NamedTemporaryFile(suffix=suffix, dir=tdir)
         if mode is None:
@@ -124,12 +124,12 @@ def generate_source_tar(
         with tarfile.open(fileobj=source, mode=mode) as tar_file:
             tar_info = tarfile.TarInfo('foo')
             tar_info.size = len(data)
-            tar_file.addfile(tar_info, six.StringIO(data))
+            tar_file.addfile(tar_info, six.BytesIO(data))
 
         source.seek(0)
         return source
 
-    def generate_source_garbage(self, suffix='.zip', data='g' * (2 ** 21)):
+    def generate_source_garbage(self, suffix='.zip', data=b'g' * (2 ** 21)):
         tdir = temp.gettempdir()
         source = temp.NamedTemporaryFile(suffix=suffix, dir=tdir)
         source.write(data)
@@ -284,7 +284,7 @@ def test_check_agreement_okay(self):
         response = self.client.get(reverse('devhub.submit.distribution'))
         assert response.status_code == 200
         # No error shown for a redirect from previous step.
-        assert 'This field is required' not in response.content
+        assert b'This field is required' not in response.content
 
     def test_submit_notification_warning(self):
         config = Config.objects.create(
@@ -327,14 +327,14 @@ def test_unlisted_redirects_to_next_step(self):
     def test_channel_selection_error_shown(self):
         url = reverse('devhub.submit.distribution')
         # First load should have no error
-        assert 'This field is required' not in self.client.get(url).content
+        assert b'This field is required' not in self.client.get(url).content
 
         # Load with channel preselected (e.g. back from next step) - no error.
-        assert 'This field is required' not in self.client.get(
+        assert b'This field is required' not in self.client.get(
             url, args=['listed']).content
 
         # A post submission without channel selection should be an error
-        assert 'This field is required' in self.client.post(url).content
+        assert b'This field is required' in self.client.post(url).content
 
 
 class TestAddonSubmitUpload(UploadTest, TestCase):
@@ -470,8 +470,8 @@ def test_default_supported_platforms(self):
         assert addon.current_version.supported_platforms == [amo.PLATFORM_ALL]
 
         # And check that compatible apps have a sensible default too
-        apps = addon.current_version.compatible_apps.keys()
-        assert sorted(apps) == sorted([amo.FIREFOX, amo.ANDROID])
+        apps = [app.id for app in addon.current_version.compatible_apps.keys()]
+        assert sorted(apps) == sorted([amo.FIREFOX.id, amo.ANDROID.id])
 
     @mock.patch('olympia.devhub.views.auto_sign_file')
     def test_one_xpi_for_multiple_apps_unlisted_addon(
@@ -661,7 +661,7 @@ def test_submit_source(self):
         assert self.get_version().source
         assert self.addon.needs_admin_code_review
         mode = (
-            oct(os.stat(self.get_version().source.path)[stat.ST_MODE]))
+            '0%o' % (os.stat(self.get_version().source.path)[stat.ST_MODE]))
         assert mode == '0100644'
 
     def test_submit_source_targz(self):
@@ -672,7 +672,7 @@ def test_submit_source_targz(self):
         assert self.get_version().source
         assert self.addon.needs_admin_code_review
         mode = (
-            oct(os.stat(self.get_version().source.path)[stat.ST_MODE]))
+            '0%o' % (os.stat(self.get_version().source.path)[stat.ST_MODE]))
         assert mode == '0100644'
 
     def test_submit_source_tgz(self):
@@ -684,7 +684,7 @@ def test_submit_source_tgz(self):
         assert self.get_version().source
         assert self.addon.needs_admin_code_review
         mode = (
-            oct(os.stat(self.get_version().source.path)[stat.ST_MODE]))
+            '0%o' % (os.stat(self.get_version().source.path)[stat.ST_MODE]))
         assert mode == '0100644'
 
     def test_submit_source_tarbz2(self):
@@ -696,7 +696,7 @@ def test_submit_source_tarbz2(self):
         assert self.get_version().source
         assert self.addon.needs_admin_code_review
         mode = (
-            oct(os.stat(self.get_version().source.path)[stat.ST_MODE]))
+            '0%o' % (os.stat(self.get_version().source.path)[stat.ST_MODE]))
         assert mode == '0100644'
 
     @override_settings(FILE_UPLOAD_MAX_MEMORY_SIZE=1)
@@ -734,7 +734,7 @@ def test_submit_source_in_memory_upload(self):
         assert self.get_version().source
         assert self.addon.needs_admin_code_review
         mode = (
-            oct(os.stat(self.get_version().source.path)[stat.ST_MODE]))
+            '0%o' % (os.stat(self.get_version().source.path)[stat.ST_MODE]))
         assert mode == '0100644'
 
     @override_settings(FILE_UPLOAD_MAX_MEMORY_SIZE=2 ** 22)
@@ -748,7 +748,7 @@ def test_submit_source_in_memory_upload_with_targz(self):
         assert self.get_version().source
         assert self.addon.needs_admin_code_review
         mode = (
-            oct(os.stat(self.get_version().source.path)[stat.ST_MODE]))
+            '0%o' % (os.stat(self.get_version().source.path)[stat.ST_MODE]))
         assert mode == '0100644'
 
     def test_with_bad_source_extension(self):
@@ -790,7 +790,7 @@ def test_with_bad_source_not_an_actual_archive(self):
     def test_with_bad_source_broken_archive(self):
         source = self.generate_source_zip(
             data='Hello World', compression=zipfile.ZIP_STORED)
-        data = source.read().replace('Hello World', 'dlroW olleH')
+        data = source.read().replace(b'Hello World', b'dlroW olleH')
         source.seek(0)  # First seek to rewrite from the beginning
         source.write(data)
         source.seek(0)  # Second seek to reset like it's fresh.
@@ -1064,7 +1064,7 @@ def test_akismet_spam_check_spam_logging_only(self, comment_check_mock):
         assert report.comment_type == 'product-name'
         assert report.comment == u'spám'
         assert text_type(self.addon.name) == u'spám'
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
         comment_check_mock.assert_called_once()
 
@@ -1082,7 +1082,7 @@ def test_akismet_spam_check_ham(self, comment_check_mock):
         report = AkismetReport.objects.get()
         assert report.comment_type == 'product-name'
         assert report.comment == u'spám'
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
     @override_switch('akismet-spam-check', active=True)
     @mock.patch('olympia.lib.akismet.tasks.AkismetReport.comment_check')
@@ -1097,8 +1097,8 @@ def test_akismet_spam_check_no_changes(self, comment_check_mock):
     def test_name_summary_lengths_short(self):
         # check the separate name and summary labels, etc are served
         response = self.client.get(self.url)
-        assert 'Name and Summary' not in response.content
-        assert 'It will be shown in listings and searches' in response.content
+        assert b'Name and Summary' not in response.content
+        assert b'It will be shown in listings and searches' in response.content
 
         data = self.get_dict(name='a', summary='b')
         self.is_success(data)
@@ -1112,7 +1112,7 @@ def test_name_summary_lengths_long(self):
     def test_name_summary_lengths_content_optimization(self):
         # check the combined name and summary label, etc are served
         response = self.client.get(self.url)
-        assert 'Name and Summary' in response.content
+        assert b'Name and Summary' in response.content
 
         # name and summary are too short
         response = self.client.post(
@@ -1721,7 +1721,7 @@ def test_finish_submitting_listed_static_theme(self):
         assert links[1].attrib['href'] == reverse('devhub.themes')
 
         # Text is static theme specific.
-        assert "This version will be available after it passes review." in (
+        assert b'This version will be available after it passes review.' in (
             response.content)
         # Show the preview we started generating just after the upload step.
         imgs = content('section.addon-submission-process img')
@@ -1998,7 +1998,7 @@ def test_static_theme_wizard(self):
         assert doc('#theme-header').attr('data-existing-header') == (
             'header.png')
         # No warning about extra properties
-        assert 'are unsupported in this wizard' not in response.content
+        assert b'are unsupported in this wizard' not in response.content
 
         # And then check the upload works.
         path = os.path.join(
@@ -2056,7 +2056,7 @@ def test_static_theme_wizard_unsupported_properties(self):
         assert doc('#accentcolor').attr('value') == '#123456'
         assert doc('#textcolor').attr('value') == 'rgba(1,2,3,0.4)'
         # Warning about extra properties this time:
-        assert 'are unsupported in this wizard' in response.content
+        assert b'are unsupported in this wizard' in response.content
         unsupported_list = doc('.notification-box.error ul.note li')
         assert unsupported_list.length == 3
         assert 'tab_line' in unsupported_list.text()
@@ -2301,8 +2301,8 @@ def test_show_request_for_information(self):
             user=self.user, details={'comments': 'this is an info request'})
         response = self.client.get(self.url)
         assert response.status_code == 200
-        assert 'this should not be shown' not in response.content
-        assert 'this is an info request' in response.content
+        assert b'this should not be shown' not in response.content
+        assert b'this is an info request' in response.content
 
     def test_dont_show_request_for_information_if_none_pending(self):
         ActivityLog.create(
@@ -2313,8 +2313,8 @@ def test_dont_show_request_for_information_if_none_pending(self):
             user=self.user, details={'comments': 'this is an info request'})
         response = self.client.get(self.url)
         assert response.status_code == 200
-        assert 'this should not be shown' not in response.content
-        assert 'this is an info request' not in response.content
+        assert b'this should not be shown' not in response.content
+        assert b'this is an info request' not in response.content
 
     def test_clear_request_for_information(self):
         AddonReviewerFlags.objects.create(
@@ -2474,7 +2474,7 @@ def test_akismet_spam_check_spam_logging_only(self, comment_check_mock):
         report = AkismetReport.objects.last()
         assert report.comment_type == 'product-summary'
         assert report.comment == u'Delicious Bookmarks is the official'
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
         assert comment_check_mock.call_count == 2
 
@@ -2498,7 +2498,7 @@ def test_akismet_spam_check_ham(self, comment_check_mock):
         report = AkismetReport.objects.last()
         assert report.comment_type == 'product-summary'
         assert report.comment == u'Delicious Bookmarks is the official'
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
 
         assert comment_check_mock.call_count == 2
 
@@ -2512,7 +2512,7 @@ def test_akismet_spam_check_no_changes(self, comment_check_mock):
 
         # No changes but both values were spam checked.
         assert AkismetReport.objects.count() == 2
-        assert 'spam' not in response.content
+        assert b'spam' not in response.content
         assert comment_check_mock.call_count == 2
 
 
diff --git a/src/olympia/devhub/tests/test_views_validation.py b/src/olympia/devhub/tests/test_views_validation.py
index 2e12559fccc9..5f9c82875cd8 100644
--- a/src/olympia/devhub/tests/test_views_validation.py
+++ b/src/olympia/devhub/tests/test_views_validation.py
@@ -49,7 +49,7 @@ def test_date_on_upload(self):
 
     def test_upload_processed_validation_error(self):
         addon_file = open(
-            'src/olympia/devhub/tests/addons/invalid_webextension.xpi')
+            'src/olympia/devhub/tests/addons/invalid_webextension.xpi', 'rb')
         response = self.client.post(reverse('devhub.upload'),
                                     {'name': 'addon.xpi',
                                      'upload': addon_file})
@@ -119,8 +119,8 @@ def setUp(self):
         self.user = UserProfile.objects.get(email='del@icio.us')
         self.file_validation = FileValidation.objects.get(pk=1)
         self.file = self.file_validation.file
-        with storage.open(self.file.file_path, 'w') as f:
-            f.write('<pretend this is an xpi>\n')
+        with storage.open(self.file.file_path, 'wb') as f:
+            f.write(b'<pretend this is an xpi>\n')
         self.addon = self.file.version.addon
         args = [self.addon.slug, self.file.id]
         self.url = reverse('devhub.file_validation', args=args)
@@ -229,7 +229,7 @@ def test_context_and_content(self):
         response = self.client.get(reverse('devhub.validate_addon'))
         assert response.status_code == 200
 
-        assert 'this tool only works with legacy' not in response.content
+        assert b'this tool only works with legacy' not in response.content
 
         doc = pq(response.content)
         assert doc('#upload-addon').attr('data-upload-url') == (
@@ -246,13 +246,13 @@ def test_filename_not_uuidfied(self, validate_mock):
 
         fpath = 'src/olympia/files/fixtures/files/webextension_no_id.xpi'
 
-        with open(fpath) as file_:
+        with open(fpath, 'rb') as file_:
             self.client.post(url, {'upload': file_})
 
         upload = FileUpload.objects.get()
         response = self.client.get(
             reverse('devhub.upload_detail', args=(upload.uuid.hex,)))
-        assert 'Validation Results for webextension_no_id' in response.content
+        assert b'Validation Results for webextension_no_id' in response.content
 
     @mock.patch('olympia.devhub.tasks.run_addons_linter')
     def test_upload_listed_addon(self, validate_mock):
@@ -279,7 +279,7 @@ def test_upload_unlisted_addon(self, validate_mock):
 
         fpath = 'src/olympia/files/fixtures/files/webextension_no_id.xpi'
 
-        with open(fpath) as file_:
+        with open(fpath, 'rb') as file_:
             self.client.post(url, {'upload': file_})
 
         assert (
@@ -338,7 +338,7 @@ def upload(self, view, **kw):
             'src/olympia/files/fixtures/files/'
             'webextension_validation_error.zip')
 
-        with open(fpath) as file_:
+        with open(fpath, 'rb') as file_:
             resp = self.client.post(reverse(view, kwargs=kw),
                                     {'upload': file_})
             assert resp.status_code == 302
@@ -391,9 +391,9 @@ def setUp(self):
         self.user = UserProfile.objects.get(email='del@icio.us')
         self.file = File.objects.get(pk=100456)
         # Move the file into place as if it were a real file
-        with storage.open(self.file.file_path, 'w') as dest:
+        with storage.open(self.file.file_path, 'wb') as dest:
             fpath = self.file_fixture_path('webextension_validation_error.zip')
-            shutil.copyfileobj(open(fpath), dest)
+            shutil.copyfileobj(open(fpath, 'rb'), dest)
         self.addon = self.file.version.addon
 
     def tearDown(self):
@@ -528,7 +528,7 @@ def test_linkify_validation_messages(self, v):
 
     def test_opensearch_validation(self):
         addon_file = open(
-            'src/olympia/files/fixtures/files/opensearch/sp_no_url.xml')
+            'src/olympia/files/fixtures/files/opensearch/sp_no_url.xml', 'rb')
         response = self.client.post(
             reverse('devhub.upload'),
             {'name': 'sp_no_url.xml', 'upload': addon_file})
diff --git a/src/olympia/devhub/tests/test_views_versions.py b/src/olympia/devhub/tests/test_views_versions.py
index f2386581bc6f..15e4794cb598 100644
--- a/src/olympia/devhub/tests/test_views_versions.py
+++ b/src/olympia/devhub/tests/test_views_versions.py
@@ -786,8 +786,8 @@ def test_show_request_for_information(self):
             user=self.user, details={'comments': 'this is an info request'})
         response = self.client.get(self.url)
         assert response.status_code == 200
-        assert 'this should not be shown' not in response.content
-        assert 'this is an info request' in response.content
+        assert b'this should not be shown' not in response.content
+        assert b'this is an info request' in response.content
 
     def test_dont_show_request_for_information_if_none_pending(self):
         self.user = UserProfile.objects.latest('pk')
@@ -799,8 +799,8 @@ def test_dont_show_request_for_information_if_none_pending(self):
             user=self.user, details={'comments': 'this is an info request'})
         response = self.client.get(self.url)
         assert response.status_code == 200
-        assert 'this should not be shown' not in response.content
-        assert 'this is an info request' not in response.content
+        assert b'this should not be shown' not in response.content
+        assert b'this is an info request' not in response.content
 
     def test_clear_request_for_information(self):
         AddonReviewerFlags.objects.create(
@@ -901,8 +901,8 @@ def test_add_appversion(self):
             initial_count=1)
         response = self.client.post(self.url, data)
         assert response.status_code == 302
-        apps = self.get_version().compatible_apps.keys()
-        assert sorted(apps) == sorted([amo.FIREFOX, amo.ANDROID])
+        apps = [app.id for app in self.get_version().compatible_apps.keys()]
+        assert sorted(apps) == sorted([amo.FIREFOX.id, amo.ANDROID.id])
         assert list(ActivityLog.objects.all().values_list('action')) == (
             [(amo.LOG.MAX_APPVERSION_UPDATED.id,)])
 
@@ -944,13 +944,13 @@ def test_delete_appversion(self):
         # Add android compat so we can delete firefox.
         self.test_add_appversion()
         form = self.client.get(self.url).context['compat_form']
-        data = map(initial, form.initial_forms)
+        data = list(map(initial, form.initial_forms))
         data[0]['DELETE'] = True
         response = self.client.post(
             self.url, self.formset(*data, initial_count=2))
         assert response.status_code == 302
-        apps = self.get_version().compatible_apps.keys()
-        assert apps == [amo.ANDROID]
+        apps = [app.id for app in self.get_version().compatible_apps.keys()]
+        assert apps == [amo.ANDROID.id]
         assert list(ActivityLog.objects.all().values_list('action')) == (
             [(amo.LOG.MAX_APPVERSION_UPDATED.id,)])
 
diff --git a/src/olympia/devhub/utils.py b/src/olympia/devhub/utils.py
index 23031e27085b..7f455ce3dacb 100644
--- a/src/olympia/devhub/utils.py
+++ b/src/olympia/devhub/utils.py
@@ -211,7 +211,7 @@ def find_previous_version(addon, file, version_string, channel):
     vint = version_int(version_string)
     for file_ in qs.order_by('-id'):
         # Only accept versions which come before the one we're validating.
-        if file_.version.version_int < vint:
+        if (file_.version.version_int or 0) < vint:
             return file_
 
 
diff --git a/src/olympia/devhub/views.py b/src/olympia/devhub/views.py
index ed9725467473..6cd0118ca85c 100644
--- a/src/olympia/devhub/views.py
+++ b/src/olympia/devhub/views.py
@@ -918,11 +918,11 @@ def ajax_upload_image(request, upload_type, addon_id=None):
             if is_icon:
                 errors.append(
                     ugettext('Please use images smaller than %dMB.')
-                    % (max_size / 1024 / 1024))
+                    % (max_size // 1024 // 1024))
             if is_persona:
                 errors.append(
                     ugettext('Images cannot be larger than %dKB.')
-                    % (max_size / 1024))
+                    % (max_size // 1024))
 
         if image_check.is_image() and is_persona:
             persona, img_type = upload_type.split('_')  # 'header' or 'footer'
@@ -938,9 +938,9 @@ def ajax_upload_image(request, upload_type, addon_id=None):
         if image_check.is_image() and content_waffle and is_preview:
             min_size = amo.ADDON_PREVIEW_SIZES.get('min')
             # * 100 to get a nice integer to compare against rather than 1.3333
-            required_ratio = min_size[0] * 100 / min_size[1]
+            required_ratio = min_size[0] * 100 // min_size[1]
             actual_size = image_check.size
-            actual_ratio = actual_size[0] * 100 / actual_size[1]
+            actual_ratio = actual_size[0] * 100 // actual_size[1]
             if actual_size[0] < min_size[0] or actual_size[1] < min_size[1]:
                 # L10n: {0} is an image width (in pixels), {1} is a height.
                 errors.append(
diff --git a/src/olympia/files/utils.py b/src/olympia/files/utils.py
index 7bac866bfb5b..b5f60672d37e 100644
--- a/src/olympia/files/utils.py
+++ b/src/olympia/files/utils.py
@@ -862,16 +862,18 @@ def extract_extension_to_dest(source, dest=None, force_fsync=False):
         target = dest
 
     try:
-        if source.endswith(('.zip', '.xpi')):
-            zip_file = SafeZip(source, force_fsync=force_fsync)
-            zip_file.extract_to_dest(target)
-        elif source.endswith(('.tar.gz', '.tar.bz2', '.tgz')):
+        source = force_text(source)
+        if source.endswith((u'.zip', u'.xpi')):
+            with open(source, 'rb') as source_file:
+                zip_file = SafeZip(source_file, force_fsync=force_fsync)
+                zip_file.extract_to_dest(target)
+        elif source.endswith((u'.tar.gz', u'.tar.bz2', u'.tgz')):
             tarfile_class = (
                 tarfile.TarFile
                 if not force_fsync else FSyncedTarFile)
             with tarfile_class.open(source) as archive:
                 archive.extractall(target)
-        elif source.endswith('.xml'):
+        elif source.endswith(u'.xml'):
             shutil.copy(source, target)
             if force_fsync:
                 FSyncMixin()._fsync_file(target)