Internal Server Error 500 on POST requests containing non-ASCII characters (multipart/form-data with a picture)

[patricks-dev]

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What did you do?

Apply a slight modification to the example from README.md under Quickstart, so it would accept POST requests. Then start the test server and post a multipart/form-data including a picture, with curl:

curl -v -F filename=picture.jpg -F upload=@/full/path/to/picture.jpg http://localhost:8080

What did you expect to see?

"Hello World!"

What did you see instead?

*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> POST / HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.81.0
> Accept: */*
> Content-Length: 2175522
> Content-Type: multipart/form-data; boundary=------------------------c892a83a67802793
> Expect: 100-continue
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 100 Continue
* Mark bundle as not supporting multiuse
< HTTP/1.1 100 Continue
* We are completely uploaded and fine
* Mark bundle as not supporting multiuse
< HTTP/1.1 500 INTERNAL SERVER ERROR
< Server: Werkzeug/3.0.0 Python/3.10.12
< Date: Wed, 11 Oct 2023 09:11:02 GMT
< Content-Type: text/html; charset=utf-8
< Content-Length: 21974
< Connection: close

[...]

ValueError: string argument should contain only ASCII characters // Werkzeug Debugger

[...]

Traceback:
File "/usr/lib/python3.10/base64.py", line 37, in _bytes_from_decode_data

[...]

During handling of the above exception, another exception occurred:
File "~/.local/lib/python3.10/site-packages/flask/app.py, line 2213, in __call__

[...]

The WSGI server calls the Flask application object as the WSGI application. This calls :meth:`wsgi_app`, which can be wrapped to apply middleware.

[...]

What version of Python are you using (python --version)?

Python 3.10.12

Does this issue reproduce with the latest release?

Yes