Database error in Simple Tab Groups

Unfortunately, an error occurred while reading data from the STG addon from the Firefox database. At the moment, the addon is stopped. To resume the add-on, do the following:

Restart Firefox Browser (for Linux and Mac OS with process termination)

If you see this window again, try reinstalling the addon:
  1. Remove STG Addon
  2. Restart Firefox Browser
  3. Install STG Addon
  4. Restore the latest STG addon data backup located in the Firefox downloads folder "STG-backups"
    You can restore backup in addon settings