[Django] #31418: ValueError when FileBasedCache is used in Python 2.7
Django
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Reporter: mastizada | Owner: nobody
Type: Bug | Status: new
Component: Core (Cache system) | Version: 2.2
Severity: Release blocker | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Using FileBasedCache in Django 2.2.12 with Python 2.7.3 is giving
ValueError: unsupported pickle protocol: 5
Checking the highest protocol version for pickle using
`pickle.HIGHEST_PROTOCOL` is giving 4, so the protocol 5 is not available.
Line that is causing the error: `filebased.py` in `_is_expired` at line
146, `exp = pickle.load(f)`.
Using Python 3.8.0 solves the problem.
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Ticket URL: <https://code.djangoproject.com/ticket/31418>
Django <https://code.djangoproject.com/>
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Django
Reporter: mastizada | Owner: nobody
Type: Bug | Status: new
Component: Core (Cache system) | Version: 2.2
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Hasan Ramezani):
[https://docs.djangoproject.com/en/3.0/faq/install/#what-python-version-
can-i-use-with-django Django 2.2 doesn't support Python2.7]
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Ticket URL: <https://code.djangoproject.com/ticket/31418#comment:1>
Django
Reporter: mastizada | Owner: nobody
Type: Bug | Status: closed
Component: Core (Cache system) | Version: 2.2
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Changes (by Carlton Gibson):
* status: new => closed
* resolution: => invalid
Comment:
Django 1.11 was the last version of Django to support Python 2.7
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Ticket URL: <https://code.djangoproject.com/ticket/31418#comment:2>
Django
Reporter: mastizada | Owner: nobody
Type: Bug | Status: closed
Component: Core (Cache system) | Version: 2.2
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Simon Charette):
You likely serialized data using Python 3 and are trying to deserialize it
using Python 2. Django 2.2 also doesn't support Python 2 at all.
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Ticket URL: <https://code.djangoproject.com/ticket/31418#comment:3>
Django
-------------------------------------+-------------------------------------
Reporter: mastizada | Owner: nobody
Type: Bug | Status: closed
Component: Core (Cache system) | Version: 2.2
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Old description:
> Using FileBasedCache in Django 2.2.12 with Python 2.7.3 is giving
> ValueError: unsupported pickle protocol: 5
>
> Checking the highest protocol version for pickle using
> `pickle.HIGHEST_PROTOCOL` is giving 4, so the protocol 5 is not
> available.
>
> Line that is causing the error: `filebased.py` in `_is_expired` at line
> 146, `exp = pickle.load(f)`.
>
> Using Python 3.8.0 solves the problem.
New description:
Using FileBasedCache in Django 2.2.12 with Python 3.7.3 is giving
ValueError: unsupported pickle protocol: 5
Checking the highest protocol version for pickle using
`pickle.HIGHEST_PROTOCOL` is giving 4, so the protocol 5 is not available.
Line that is causing the error: `filebased.py` in `_is_expired` at line
146, `exp = pickle.load(f)`.
Using Python 3.8.0 solves the problem.
--
Comment (by mastizada):
Indicated the wrong python version
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Ticket URL: <https://code.djangoproject.com/ticket/31418#comment:4>
Django
-------------------------------------+-------------------------------------
Reporter: mastizada | Owner: nobody
Type: Bug | Status: closed
Component: Core (Cache system) | Version: 2.2
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by mastizada):
Replying to [comment:3 Simon Charette]:
> You likely serialized data using Python 3 and are trying to deserialize
it using Python 2. Django 2.2 also doesn't support Python 2 at all.
I'm so sorry, I wrote python 2.7 instead of 3.7.
Project was working before, I updated the Django version from 2.2.9 to
2.2.12 and then started to get this error.
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Ticket URL: <https://code.djangoproject.com/ticket/31418#comment:5>
Django
-------------------------------------+-------------------------------------
Reporter: mastizada | Owner: nobody
Type: Bug | Status: closed
Component: Core (Cache system) | Version: 2.2
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Simon Charette):
Python 3.8 introduced [https://www.python.org/dev/peps/pep-0574/ pickle
protocol 5] and pointed `pickle.HIGHEST_PROTOCOL` at it. You most likely
ran your project on Python 3.8 and stored things in a cache using the
`FileBasedCache` backend and then tried running your project on Python
3.7.
If you're in process of migrating from 3.7 to 3.8 you'll likely want to
subclass `FileBasedCache` and set its `pickle_protocol` to `4` and use it
as your backend during the transition period. When you've fully migrated
to Python 3.8 you can swap back to `FileBasedCache`.
I had to do similar manipulations when moving projects from Python 2 to 3
which makes me wonder if we should add a `CACHE_PICKLE_PROTOCOL` setting
or allow to specify it via `CACHES['OPTIONS']` to avoid having to
subclassing backends when such a transition is required. This is likely to
be more of an issue as more and more people migrate to 3.8.
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Ticket URL: <https://code.djangoproject.com/ticket/31418#comment:6>
Django
-------------------------------------+-------------------------------------
Reporter: mastizada | Owner: nobody
Type: Bug | Status: closed
Component: Core (Cache system) | Version: 2.2
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Comment (by mastizada):
Replying to [comment:6 Simon Charette]:
> If you're in the process of migrating from 3.7 to 3.8 you'll likely want
to subclass `FileBasedCache` and set its `pickle_protocol` to `4` and use
it as your backend during the transition period. When you've fully
migrated to Python 3.8 you can swap back to `FileBasedCache`.
I also was thinking about the cache, that is why I deleted everything in
the cache folder (/tmp/django/) but that didn't solve the error, it
happened again at the second load of the page.
I think having ability to set the pickle protocol version as an option
would benefit too.
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Ticket URL: <https://code.djangoproject.com/ticket/31418#comment:7>