diff --git a/openassessment/__init__.py b/openassessment/__init__.py
index 2d1e42453b..f4a42b0cee 100644
--- a/openassessment/__init__.py
+++ b/openassessment/__init__.py
@@ -2,4 +2,4 @@
 Initialization Information for Open Assessment Module
 """
 
-__version__ = '6.0.24'
+__version__ = '6.0.25'
diff --git a/openassessment/xblock/apis/assessments/peer_assessment_api.py b/openassessment/xblock/apis/assessments/peer_assessment_api.py
index 5a33e217ef..fcdb4eb812 100644
--- a/openassessment/xblock/apis/assessments/peer_assessment_api.py
+++ b/openassessment/xblock/apis/assessments/peer_assessment_api.py
@@ -156,10 +156,20 @@ def get_peer_submission(self):
             logger.exception(err)
         return peer_submission
 
-    def assert_assessed_submission_uuid_matches(self, uuid_client):
-        submission = self.get_peer_submission() or {}
+    def assert_assessing_valid_submission(self, uuid_client):
+        """
+        Validate that the forntend and backend agree on which submission is being assessed
+        """
+        # Get the current active submission without pulling a new one
+        submission = self.get_active_assessment_submission()
+
+        # If there is no active submission (expired or never got one somehow), raise
+        if submission is None:
+            raise ServerClientUUIDMismatchException()
+
         uuid_server = submission.get("uuid", None)
 
+        # If the server and client don't agree, raise
         if uuid_server != uuid_client:
             logger.warning(
                 "Irrelevant assessment submission: expected '%s', got '%s'",
@@ -207,8 +217,7 @@ def peer_assess(
     if not workflow_data.has_workflow:
         raise ReviewerMustHaveSubmittedException()
 
-    if assessed_submission_uuid:
-        peer_step_data.assert_assessed_submission_uuid_matches(assessed_submission_uuid)
+    peer_step_data.assert_assessing_valid_submission(assessed_submission_uuid)
 
     try:
         assessment = peer_api.create_assessment(
diff --git a/openassessment/xblock/test/test_peer.py b/openassessment/xblock/test/test_peer.py
index af49158590..8af38b1972 100644
--- a/openassessment/xblock/test/test_peer.py
+++ b/openassessment/xblock/test/test_peer.py
@@ -14,7 +14,10 @@
 import pytz
 
 from openassessment.assessment.api import peer as peer_api
+from openassessment.assessment.models.peer import PeerWorkflowItem
 from openassessment.workflow import api as workflow_api
+from openassessment.xblock.apis.assessments.errors import ServerClientUUIDMismatchException
+from openassessment.xblock.apis.assessments.peer_assessment_api import peer_assess
 from openassessment.xblock.utils.data_conversion import create_submission_dict
 
 from .base import SubmissionTestMixin, XBlockHandlerTestCase, scenario
@@ -22,6 +25,7 @@
 logger = logging.getLogger(__name__)
 
 
+@ddt.ddt
 class TestPeerAssessment(XBlockHandlerTestCase, SubmissionTestMixin):
     """
     Test integration of the OpenAssessment XBlock with the peer assessment API.
@@ -308,6 +312,49 @@ def test_turbo_grading(self, xblock):
         self.assertNotIn(submission["answer"]["parts"][1]["text"], peer_response.body.decode('utf-8'))
         self.assertIn("You have successfully completed", peer_response.body.decode('utf-8'))
 
+    @scenario('data/peer_assessment_scenario.xml', user_id='Sally')
+    @ddt.data(None, "nonmatchinguuid")
+    def test_assess_expired_peer_item(self, xblock, client_uuid):
+
+        # Create two submissions, one for sally and one for Hal
+        student_item = xblock.get_student_item_dict()
+        sally_student_item = copy.deepcopy(student_item)
+        sally_student_item['student_id'] = "Sally"
+        sally_submission = self.create_test_submission(
+            xblock, student_item=sally_student_item, submission_text=("Sally's answer 1", "Sally's answer 2")
+        )
+
+        hal_student_item = copy.deepcopy(student_item)
+        hal_student_item['student_id'] = "Hal"
+        hal_submission = self.create_test_submission(
+            xblock, student_item=hal_student_item, submission_text=("Hal's answer 1", "Hal's answer 2")
+        )
+
+        # Sally is given Hal to assess
+        hal_sub = peer_api.get_submission_to_assess(sally_submission['uuid'], 1)
+        assert hal_sub['uuid'] == hal_submission['uuid']
+        assert peer_api.get_active_assessment_submission(sally_submission['uuid']) == hal_sub
+
+        # Modify the peer workflow item to be too old to be "active"
+        pwi = PeerWorkflowItem.objects.last()
+        assert pwi.submission_uuid == hal_submission['uuid']
+        pwi.started_at = pwi.started_at - dt.timedelta(days=1)
+        pwi.save()
+        assert peer_api.get_active_assessment_submission(sally_submission['uuid']) is None
+
+        # An error should be raised when sally tried to submit an assessment
+        # because she doesn't have an active submission
+        with self.assertRaises(ServerClientUUIDMismatchException):
+            peer_assess(
+                self.ASSESSMENT['options_selected'],
+                self.ASSESSMENT['overall_feedback'],
+                self.ASSESSMENT['criterion_feedback'],
+                xblock.config_data,
+                xblock.workflow_data,
+                xblock.peer_assessment_data(),
+                assessed_submission_uuid=client_uuid
+            )
+
 
 @ddt.ddt
 class TestPeerAssessmentRender(XBlockHandlerTestCase, SubmissionTestMixin):
diff --git a/package-lock.json b/package-lock.json
index 4496bc78bf..ee5dff1efa 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "edx-ora2",
-  "version": "6.0.24",
+  "version": "6.0.25",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
diff --git a/package.json b/package.json
index edae2cb717..8892c37007 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "edx-ora2",
-  "version": "6.0.24",
+  "version": "6.0.25",
   "repository": "https://github.com/openedx/edx-ora2.git",
   "dependencies": {
     "@edx/frontend-build": "8.0.6",