If you have a working thunderbird, you can save the profile. my suggestion before switching is to locate the profile, exit thunderbird, and copy it safely.

If you have a working thunderbird, you can save the profile. my suggestion before switching is to locate the profile, exit thunderbird, and copy it safely.

Will a full export do the trick? and then uninstall the old version and install the flatpack version?

I don't trust the Thunderbird export, but I do trust a file copy by the OS. I think the steps for Windows will work - click help>troubleshootinginformation - scroll down to 'profile folder'and click 'open folder' - you should now be in the profile. exit thunderbird, and then copy the contents of the profile - after installing new release, repeat the above steps to get to the profile. again, exit thunderbird and now paste the copied profile contents to overwrite the new profile. - restart thunderbird

Well I followed your steps, right up to the restoration, - click help>troubleshootinginformation - scroll down to 'profile folder'and click 'open folder' The new version of Thunderbird will not open the profile folder, I restarted Thunderbird and went in and tried again, nothing happens when I click on the "open directory" button

So seeing as how I had done an full export prior to uninstalling the System Package version of Thunderbird, I decided to give it a whirl, and ran the import, accounts came over, address books came over, calendar is blank POS