If you're using Mezzanine and s3, and you get an error like

File "/storages/backends/s3boto.py" in modified_time
  455.         return parse_ts_extended(entry.last_modified)
File "/storages/backends/s3boto.py" in parse_ts_extended
  39.         rv = parse_ts(ts)
File "/boto/utils.py" in parse_ts
  390.     ts = ts.strip()

Exception Type: AttributeError at /admin/filebrowser/browse/
Exception Value: 'NoneType' object has no attribute 'strip'

when attempting to upload a file, then fear not. This is a seemingly common error, and it comes from the django-storages package.

In a nutshell

The last_modified attribute fails to get set for a new file uploaded, so entry.last_modified in the s3boto code traceback above is None. Stripping this None object raises the exception. If you restart, you may force s3 to provide the timestamp on the next go around, and you will likely see the previously uploaded file in your media lib.

How to fix

You should be using django-storages-redux now instead of django-storages. It is the fork currently being maintained, and offers a solution to this problem and others.

Ensure that django storages is completely uninstalled from venv and system:

pip uninstall django-storages

then install redux

pip install django-storages-redux

There is no need to do anything else. The redux package can be added to INSTALLED_APPS as storages just like the regular package, and imported as storages in your scripts.

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About Lee

I am a Theoretical Physics PhD graduate now working in the technology sector. I have strong mathematical skills and originally started in heavy duting scientific computing, but now I work mostly with Python and the Django framework. I am available for hire now, so check out my resume and get in touch.