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
35868	'collectstatic' management command inappropriately eating AttributeError exceptions	Brett G		"Recently, Django 5.0 [https://docs.djangoproject.com/en/5.1/releases/5.0/#features-removed-in-5-0 removed] the `django.utils.timezone.utc` alias to `datetime.timezone.utc`.

I've written a custom file storage class that implements a `get_modified_time` method which, predictably, used the `django.utils.timezone.utc` alias.

The code in 'django/contrib/staticfiles/management/commands/collectstatic.py' reads as follows:

{{{#!python
            try:
                # When was the target file modified last time?
                target_last_modified = self.storage.get_modified_time(prefixed_path)
            except (OSError, NotImplementedError, AttributeError):
                # The storage doesn't support get_modified_time() or failed
                pass
            else:
                try:
                    # When was the source file modified last time?
                    source_last_modified = source_storage.get_modified_time(path)
                except (OSError, NotImplementedError, AttributeError):
                    pass
}}}

I assume the exception catch there is meant to ignore `AttributeError` exceptions from custom file storage classes that do not implement `get_modified_time`. This is inappropriate - custom file storage classes can be written by users, and the `get_modified_time` method may raise `AttributeError` for a completely unrelated reason. 

The net effect of this is that when `collectstatic` was run, ''all'' static files were copied, regardless of modification time, as `collectstatic` silently ignored this error. This was difficult to pin down.

Checking for the presence of a `get_modified_time` attribute using duck typing (eg. `hasattr(self.storage, 'get_modified_time')`) may be more appropriate than eating such a generic exception."	Bug	new	contrib.staticfiles	5.0	Normal				Unreviewed	0	0	0	0	1	0