Flask Session not working after latest itsdangerous package upgrade

[torre76]

Hello,

Today I had a problem while deploying a project which is based on flask and Flask-Session.
I received this error at server startup:

  File "/opt/gl/sso/env/lib/python3.6/site-packages/flask_session/__init__.py", line 16, in <module>
    from .sessions import NullSessionInterface, RedisSessionInterface, \
  File "/opt/gl/sso/env/lib/python3.6/site-packages/flask_session/sessions.py", line 23, in <module>
    from itsdangerous import Signer, BadSignature, want_bytes
ImportError: cannot import name 'want_bytes'

Digging on this issue I found that the package itsdangerous released version 1.0.0 which it has no want_bytes function anymore.

Forcing my requirements.txt with itsdangerous>=0.24,<1.0.0 solved the problem but I think you should refactor the package since itsdangerous is a main dependency of flask.

[jcollard]

👍

[tvenstad]

The file structure of the itsdangerous package has changed. The function resides in the encoding.py file. Changing the import statements from:
from itsdangerous import Signer, BadSignature, want_bytes
to:
from itsdangerous import Signer, BadSignature
from itsdangerous.encoding import want_bytes
works for me.

[davidism]

itsdangerous 1.1.0 was just released and contains a fix for this. Flask-Session should still be fixed so it doesn't rely on this, but it won't fail for now.