id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
35041	DATA_UPLOAD_MAX_MEMORY_SIZE causes a confusing error when not an integer	Dimitar Tasev	nobody	"When trying to POST to a FileField or ImageField, an error will be shown when trying to save the object (even without specifying a file) if DATA_UPLOAD_MAX_MEMORY_SIZE is not an integer.

To replicate:

{{{
# in settings.py
DATA_UPLOAD_MAX_MEMORY_SIZE = 4e7

# in models.py
from django.db import models
class FileHolder(models.Model):
    file = models.FileField(upload_to=""files"", blank=True, null=True)

# in admin,py
from django.contrib import admin
admin.site.register(FileHolder, EfasNewsAdmin)
}}}

Make migrations & migrate, then go to the Admin view of the model, create a new instance and save. There is no need to specify any file for upload, the error will be shown, here is a stacktrace with Django 4.2.8 and Python 3.11.6

{{{
Traceback (most recent call last):
  File ""/usr/local/lib/python3.11/site-packages/django/core/handlers/exception.py"", line 55, in inner
    response = get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/core/handlers/base.py"", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/contrib/admin/options.py"", line 688, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/utils/decorators.py"", line 130, in _wrapper_view
    result = middleware.process_view(request, view_func, args, kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/middleware/csrf.py"", line 470, in process_view
    self._check_token(request)
  File ""/usr/local/lib/python3.11/site-packages/django/middleware/csrf.py"", line 373, in _check_token
    request_csrf_token = request.POST.get(""csrfmiddlewaretoken"", """")
                         ^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/core/handlers/wsgi.py"", line 93, in _get_post
    self._load_post_and_files()
  File ""/usr/local/lib/python3.11/site-packages/django/http/request.py"", line 373, in _load_post_and_files
    self._post, self._files = self.parse_file_upload(self.META, data)
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/http/request.py"", line 321, in parse_file_upload
    return parser.parse()
           ^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/http/multipartparser.py"", line 123, in parse
    return self._parse()
           ^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/http/multipartparser.py"", line 235, in _parse
    data = field_stream.read(size=read_size)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/http/multipartparser.py"", line 465, in read
    return b"""".join(parts())
           ^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/http/multipartparser.py"", line 460, in parts
    emitting = chunk[:remaining]
               ~~~~~^^^^^^^^^^^^
TypeError: slice indices must be integers or None or have an __index__ method
}}}


Changing DATA_UPLOAD_MAX_MEMORY_SIZE = 4e7 to DATA_UPLOAD_MAX_MEMORY_SIZE  = 40000000 and repeating the steps will remove the error.

As far as I can tell Django doesn't do type checking of the value of the settings, at least I couldn't get other settings to fail due to invalid types. If a type check during the ""system check"" step is not possible then an additional type assertion would be good so that a better error message can be shown as only integer works.

I have only tested this through Django Admin, but the error happens inside django.http so perhaps it can be replicated via other ways of POST-ing.

Related links:
- StackOverflow question where I found the solution first: https://stackoverflow.com/questions/48865441/django-admin-typeerror-on-any-post-request"	Bug	new	File uploads/storage	4.2	Normal				Unreviewed	0	0	0	0	1	0