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We suddenly started getting this issue when compressing django static files on production servers. Ubuntu 16.04, Python 3.x, Django 1.11. I am using an ansible-playbook to deploy.

The error is as follows:

CommandError: An error occurred during rendering /chalktalk/app/chalktalk-react-40/chalktalk-react-40/chalktalk/apps/exams/templates/exams/section-edit.html: Invalid input of type: 'CacheKey'. Convert to a byte, string or number first.

It doesn't seem to be an issue in one of the static files but a general issue. Every time we run it, we get a different file.

I was looking for any clues on google and nothing shows up with the same error.

nael
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    Good timing! I am damn sure all using django-redis must have been broken their prod environments with the unexpected backward incompatible changes. – Babu Nov 19 '18 at 09:16
  • @Babu It only broke our CI. Its not really the fault of redis-py, after all it was a _major_ version bump so compatibility is explicitly not expected. django-redis should have been restricting what versions they allow, but even that is not an "incompatible change" on their part, just a bug in their setup.py. – Andrew Nov 20 '18 at 05:05
  • Yeah, not blaming anyone here :) – Babu Nov 20 '18 at 18:11

2 Answers2

17

This is due to an change in the redis library between v2 and v3. Try pinning your redis version to 2.10.6 from August 17, 2017, the last redis version before the change.

pip install redis==2.10.6
# and/or
echo redis==2.10.6 >> requirements.txt

I am not sure what package you are using which may be requiring redis as a dependency, or if you are using it yourself. In either case its the same process.

In my case this shows up through the django-redis package, which requires the underlying redis package. Django-redis doesn't restrict the maximum version, so it happily upgrades past a major version bump, which you can't really do since thats where you expect the API to change!

The exact code (in my case), in master at django-redis:

install_requires = [
    "redis>=2.10.0",
]

But it should really be this

install_requires = [
    "redis>=2.10.0, <3",
]

Edit: I found the bug report in django-redis (#342) about this just now, but this SO question came up first in google when I was looking into it.

Andrew
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    Thank you Andrew. I actually have in my requirements.txt `django-redis-cache==1.6.5 celery[redis]==3.1.23 asgi-redis==1.4.3 channels-redis==2.1.0`. But I found out that the ansible playbook is installing debian packages and one of them is `redis-tools` and that has no version requirement so it is installing `3.0.6` – nael Nov 16 '18 at 15:21
  • Do I pin the redis version by just adding it to the requirements.txt file `redis==2.10.6` before the django-redis-cache and other redis dependent packages? – nael Nov 16 '18 at 15:41
  • I just added redis==2.10.6 in my requirements.txt and it worked :) – nael Nov 16 '18 at 15:57
  • @nmusleh Yes, thats all you should need if you are installing via `pip install -r requirements.txt` since it will force that version. If you are using other package managers, or if installing/upgrading manually with `--upgrade` then it will upgrade dependencies unless you tell it not to with `--no-deps`. – Andrew Nov 19 '18 at 03:04
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Try installing redis-py below version 3

Fernando Ruiz Humanes
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  • This is look like a comment please delete it and paste your proper answer and read [How to Write good answer](https://stackoverflow.com/help/how-to-answer) – Ali Nov 16 '18 at 10:40
  • Technically he is correct, though without providing any supporting docs and so on there would be no way to evaluate it. – Andrew Nov 16 '18 at 11:32