More info may help. Are you installing 115 separate from 102? That is, I don't understand why you are importing unless you have two, or if you uninstalled 102? Or maybe something else? How are you doing the import? I know zip about macs, but I may be able to assist for TB. May be...

More info may help. Are you installing 115 separate from 102? That is, I don't understand why you are importing unless you have two, or if you uninstalled 102? Or maybe something else? How are you doing the import? I know zip about macs, but I may be able to assist for TB. May be...

I was importing because when I started 115 it didn't go to my existing profile but started with a blank slate. I didn't uninstall 102, it's a separate installation. I quit 102 before importing to 115, to make sure there's no interference. I'm using the Import tool from the "Tools..." menu, choosing "import from another Thunderbird profile", and selecting the default option it gives me.

Ok, I don't know mac, but I have been successful in Windows by using the OS file manager to copy the profile (when Thunderbird was not running to avoid conflict). My suggestion to you is to attempt the same. Exit TB and use Mac's file utility to copy the profile content from old to new.

Or just use the profile manager to point version 115 to the original Thunderbird profile, which probably has the name "default-release".

Or install version 115 program over top the version 102 program, which it should have done by default.

I did a normal update to 115 and it lost track of most of my POP3 messages. They seem to still be there, but the main TB window doesn't see the folders. The update seems to have created new mail folders sporadically and moved some but not all of the messages. The main TB window does not list all of my accounts. I'm using file per message storage. I think I can recover by copying messages by hand and then deleting the corresponding .msf files so that TB has to create new ones, but I haven't tried it. Any advice?

I did a normal update to 115 and it lost track of most of my POP3 messages. They seem to still be there, but the main TB window doesn't see the folders. The update seems to have created new mail folders sporadically and moved some but not all of the messages. The main TB window does not list all of my accounts. I'm using file per message storage. I think I can recover by copying messages by hand and then deleting the corresponding .msf files so that TB has to create new ones, but I haven't tried it. Any advice?

Help > Troubleshoot Mode > About:profiles will list your profiles. See also https://support.mozilla.org/en-US/kb/using-multiple-profiles

I have used several profiles for years and know how to use the profile manager and what the file structures and (more or less) what the file contents were in 102. The updates have been so reliable I didn't bother to check out 115 before I installed it. Wish I had, because I would have copied the tree to another place first for safety. I've now discovered that the 115 upgrade actually did lose a bunch of my messages. I guess those are lost forever.

So I'm no longer concerned about them except as a request that in the future, TB provide an update option to save the old installation before updating, so in the worst case as I have now, lost info and messages can be restored by downgrading back to the old version.

I still would like to restore 102 because I like the interface, and more important, depend on import/export tools, which 115 does not support. I've been told I can't reliably back up to 102 because the profile structure has been changed. I would like to know exactly what has been changed about it because I'm confident I can get into the files and restore 102 if I know what changes to make.

The new import/export is still in beta but works reliably. You can get it at https://github.com/thundernest/import-export-tools-ng/blob/v14.0.0/xpi/beta/import-export-tools-ng-14.0.0-b6-tb.xpi My suggestion for upgrades is to always do a profile backup prior to authorizing any update if you are concerned on reliability.

Yes, you can selectively take components from the old profile and copy them in to the new profile in Mail\Local Folders. I do regret that you experienced problems.

Thank you. I stand forewarned. I appreciate knowing what the situation is. I also appreciate the effort you and others put into writing and maintaining this very useful software, even though I do sometimes complain.