Missing icons at top of notebook

I’m not sure when this started, but I see “Run Selected Cell” instead of the corresponding icon. Same for other icons that are normally present above an open notebook. This is on JupyterLab 3.6.3.

I suspect this happened when I installed JupyterLab 4.0.6 on a different virtualenv. It seems it may have written some settings to a file that are seen by both versions (outside the virtualenv) that are only compatible with 4.x.

I think this warning is new on the terminal when I start 3.6.3:

[W 2023-09-27 15:36:45.341 LabApp] Failed validating settings (@jupyterlab/htmlviewer-extension:plugin): Additional properties are not allowed ('trustByDefault' was unexpected)
    Failed validating 'additionalProperties' in schema:
        {'additionalProperties': False,
         'definitions': {'toolbarItem': {'additionalProperties': False,
                                         'properties': {'args': {'title': 'Command '


I’m not sure if it’s related.

Any help is appreciated. Thanks!


Yep, user settings are stored outside your environment, so that your experience is consistent between different virtual environments. Sadly, this doesn’t always go to plan, and sadly there’s not much to be done about major version revs being incompatible with each other.

While theoretically someone (other than jupyterlab) could offer a jupyterlab-migrate-user-settings utility which shipped all the known plugin settings versions, and knew how to migrate them, a la nbformat, not sure that’s likely in a timeframe that is useful to you.

Have a look at the output of…

jupyter --paths

…in the config section

For me that happened to be ~/.jupyter/lab/user-settings/@jupyterlab/{extension}, YMMV.

Some ways forward:

  • back up that folder
  • start
    jupyter lab --LabConfig.user_settings_dir=./empty-jupyter-config
    • this should start your lab without any settings customizations
      • see if this works
      • copy settings and refresh until it breaks
      • copy that user-settings back over your “real” ones (back them up first)

Or the nuclear option:

  • back up that folder (did i mention backing up?)
    • then delete it
      • launch lab
        • then restore settings one by one (or by hand) until everything work
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I must be misunderstanding something…

jupyter lab --LabConfig.user_settings_dir=./empty-jupyter-config

doesn’t change anything. The problem is still there and all my settings are still present.

Just to be sure, when you said “back up that folder”, you didn’t mean to back it up and delete it, did you? And ./empty-jupyter-config is any empty folder, right?

Right: you’re looking to run (at least temporarily) without the contents of where user-settings are… do this either by moving them out of the way, or if sure you don’t care, just delete them.

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Just to clarify,


is unnecessary. The default folder is already empty, so this is redundant. Am I right?

Then, yes, clearing the user setting folder worked to remove the problem. I have not been through the exercise of add settings file back in, but this approach should work to identify what setting is causing the problem.

Still sad that trying a new revision breaks things in the previous one. This makes trying new major revisions risky and people will avoid it more.