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Version 18 (modified by anonymous, 7 years ago) (diff)

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Better Error Messages

Good error messages make for more productive developers. This page is a place to collect error messages that could stand improvement, or which are misleading or confusing in certain contexts. Most of us have had the experience of getting a "weird" message, puzzling it out (perhaps with help from django-users or #django) and then moving on.

Some of these may seem like quick patches but others will take a bit of consideration -- that's why the wiki page rather than individual tickets. Some are more along the lines of "Django Lint" than simple changes to error output.

For now, let's try dividing them into sections by major module. Within those sections suggested format is: error message, explanatory context (often important -- a message that is very helpful in one context can be confusing in another), suggested improvements/changes.

Also see:

django.contrib.admin

'NoneType' object has no attribute 'get_field_sets'

Context: One or more models that are referenced by ForeignKey from another model are missing their inner Admin class. Possible other causes as well. See ticket #1808.
Suggestion: Check relevant Admin settings during model validation?

  • Ticket #3219 -- suggestion for better error messages for invalid Admin attributes

django.core

TypeError at ...
string indices must be integers

Context: A FileUploadField is being validated but the form did not have enctype="multipart/form-data" set.
Suggestion: Check form enctype during validation? Show FILES in addition to GET and POST on error pages?

  • Ticket #3221 -- patch for better error message for faulty URLconf

django.db

OperationalError: Unable to close due to unfinalised statements

Context: SQLite file permissions are incorrect (directory or DB file lack write permission)
Suggestion: Check file permissions when running with SQLite backend and warn user if they seem incorrect

ProgrammingError: ERROR:  current transaction is aborted, commands ignored until end of transaction block

In certain situations with PostgreSQL, a bogus error message about SET TIME ZONE may be returned. See #3179 (which is closed, but has a description of the problem). The real error message can probably be found in the postgres log file.

django.http

AttributeError: Http404 instance has no attribute 'has_header'

Context: Http404 is returned instead of raised
Suggestion: Check type of HttpResponse before attempting to use (perhaps unPythonic?) or possibly give Http404 a clearer name like Http404Exception

django.template

FIXED

  • Ticket #1732 -- a problem that elicits no error message, but should.