BUG: potential attribute error

[aburrell]

I encountered this after upgrading ipython. An AttributeError in traitlets has stopped ipython from opening. I am not quite sure what's going on in the code after a brief peak, so thought I would bring it to your attention.

File "/opt/local/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/traitlets/config/loader.py", line 933, in __call__
    namespace._flags.append(self.flag)
AttributeError: 'Namespace' object has no attribute '_flags'

I am running OS X Mojave, python 3.9.8, and traitlets version 5.1.0. Please let me know if I can provide any more information or perform any tests that may be useful.

[ktowen]

I'm having the same error. It started after upgrading Python from 3.9.7 to 3.9.8

[mocurin]

Same issue. OS X Big Sur, launching notebooks inside VSCode on python 3.9.8 seems broken

[pmadhikar]

Did anyone have any luck with fixing this bug? I have the same problem.

Edit: This seems to be fixed in trailtlets version 5.1.1

pip install --upgrade traitlets

[rmorshea]

@Carreau it looks like Jupyter should bump the minimum version of traitlets it depends on (assuming the upgrade does in fact fix this).