How can I remove a theme that is no longer in core? Drush/Drupal 8 is throwing errors because a theme is 'enabled' that is 'missing'. The theme is/was part of core (test_stable), and I'm having difficulty getting it to uninstall.
I understand that the theme code needs to be there in order to uninstall, but this being core makes that difficult. I can manually place the module there locally, but would need to create a patch to actually have it installed (and then uninstalled) on the remote environments via composer.
The &quot;Module Missing Message Fixer&quot; module addresses this scenario with modules, but not themes.
I'm pretty sure enabling this theme in the first place was an accident. I'm hoping someone can help me determine if there is a way to do this w/out creating a patch that installs this old theme.
You can create a theme calling it test_stable. Then, you clear the cache with drush cr and uninstall the theme with drush theme:uninstall test_stable. It will solve your problem.
You don't need to create the whole theme; the test_stable.info.yml file is sufficient for Drupal to recognize the theme as present.
As the test_stable theme has been removed from Drupal after Drupal 8.7.x, and that file isn't present in latest versions, before proceeding with what I suggested, I would run drush updbst and check for pending updates.