Thunderbird can't find existing user profile

There’s something not user-friendly here.
Alan’s tip does not work. TB --profile-manager does not take account of the new data.

Running TB 78.2.1 (edge channel at the moment) I had to:

  • launch TB snap
  • close TB snap
  • delete the snap profile’s folder content
  • copy all the old profile folder content in the snap profile folder
  • launch TB snap
  • remove all the unused langpacks in TB extensions menu (to have full native language in TB)
  • restart TB