I suggest you install 68.2 as it does contain some mac specific fixes. https://www.thunderbird.net/en-US/thunderbird/all/

otherwise I suggest you delete the file "foldertree.json" from the profile (with Thunderbird not running) as is is a cache of the folder pane and appear to occasionally become corrupted.

68.2? I'm on a Mac. It looks like 60.9.0 is the current version.

I opened the new profile a second time, and the (IMAP) inbox has completely disappeared. It looks like each time I start Thunderbird into this profile, it makes some new folder structure files; I have "Drafts-1, Sent-1, Sent, Trash, INBOX-1.msf, INBOX-2.msf, INBOX-3.msf, INBOX.msf ..." and even "mail.ncf-1.ca" in addition to "mail.ncf.ca"

I tried deleting "foldertree.json". Unfortunately, this didn't help.

Weird bug...

dispo.co9z said

68.2? I'm on a Mac. It looks like 60.9.0 is the current version.

Did you go to the link I provided and download it. Or just check for updates which WILL NOT WORK at this time for V68 which is why I provided a link.

Seriously. I am guessing your mail server is mail.ncf-1.ca. For that to appear there "should" be such a folder in the profile. It is something I would normally associate with the copy being pasted over the original one level to far down. The creation of "Numbered" folders is usually due to access to the originals in the file system being blocked. ie Inbox exists but is unavailable so inbox-1 is created. I have seen this sort of thing in the past under Windows with anti virus products locking files the program needs. I have also seen it when the file system has issues with the ownership of the files. I suggest you check some of the files and see what properties they have with regard to read / write.

Hmm. Thanks for the additional information. Now I have updated to version 68. This time, I even tried using MacOS's "Duplicate Exactly" function instead of just copy-pasting, to make a more exact copy of my old profile folder's contents. Then I renamed it to match the new profile folder's name. I checked file permissions and they seem to be the same... Unfortunately, it is still doing this strange behaviour.

One more clue that might be helpful, possibly: I notice that the 'tabs' I had open in the old profile did not carry over to the new one. So clearly, even though I'm using "Duplicate Exactly", *not all* of the information from the old profile is surviving the copying process into the new profile. Still not sure how to fix this, but at least it could be one more clue.

To describe the problem again, the first time I open TB under the new profile, it has "INBOX-1", "Sent-1" folders, etc. in addition to "INBOX", "Sent", (i.e. there's more folders than there should be) and each of these folders contains some (but not all) of my emails. I think the "Inbox-1" folder contained the correct full set of emails, while the "INBOX" one was a smaller set of emails... But then, when I quit and re-open under the new profile a second time, the whole tree structure under "INBOX" is gone.

I've been doing this in "offline" mode, so maybe that has something to do with it? Maybe because I'm not letting the IMAP mailbox load itself up again?

My mail server is mail.ncf.ca , not mail.ncf-1.ca.

Please do let me know if you have any other ideas. Thanks for your help.

The tabs are stored in the session.json file in the profile. Was Thunderbird running when you moved the profile? (make sure it is not)

I also suggest you copy all files from the .thunderbird folder in the library to the new device, not just the profile. Including the profiles.ini file in the .Thunderbird folder.

Thunderbird 68 makes some major changes to profiles and profile handling. What we thought we knew is now obsolete and I for one am still trying to work out exactly how the changes work (at least when they don't work as they are expected to.)