You might have a broken layout. Run 68 in safe mode (hold Option when launching) and see if the menus are active.

Same problem. Might it be better to try to update to an intermediate version of 68? It is only that one menu item that doesn't work.

I don't know if an earlier version would work, but all releases are here:

https://archive.mozilla.org/pub/thunderbird/releases/

Does the keyboard shortcut work (command+.)?

You might want to try a new profile: Help/Troubleshooting, about:profiles.

I can highlight the items in the "Thunderbird" dropdown menu, it is just that nothing happens when I click them. All other dropdown menu lists work fine.

Have gone back to 60.9.1, and tried upgrading from that again, same thing, but I the upgrade file has already been downloaded somewhere and it goes right to "restart to upgrade" rather than downloading. Perhaps there was something wrong with the downloaded file - I'd like to delete it and try again, but I don't know where the Mac put it.

I suppose I could go for a naive install of 68 and see if that works, but I would need to know how to add my current (saved) Profile to that.

I just downloaded and installed from the v68.8.dmg. Same thing.

Uninstalling and re-installing the program doesn't affect the profile folder, so if that's where the issue lies, it's best to create a new profile to test. If the new profile works, data from the old profile can be transferred to the new one.

I ran 68.8.dmg again, but this time having moved the profile fold out of its default location, so that v68.8 would have to make its own. I did not set up any accounts in v68.8 - but the drop-down elements worked. I exited TB, then I replaced the new (essentially empty) profile folder with the previous one. Ran TB, which read all the files and accounts - but the dropdown elements did not work.

SO - it is definitely some element of the (fully functional) profile folder I am using in v60.9.1 that is causing a problem in v68.

What is the best way to make a new profile yet transfer into it all the essential components of the accounts, local files (and maybe add-ons) without also transferring over a possibly problematic element? Thanks!

Add your accounts to the new profile and install the necessary add-ons. Mail for IMAP accounts will be downloaded at the first connection. For POP accounts or local mail, copy the mbox files - the large files with no extensions, named after folders - from the account subfolders of Mail in the old profile, e.g. Mail/pop.gmail.com, and also in Mail/Local Folders, to Mail/Local Folders in the new profile. Copy abook.mab and history.mab (Personal Address Book & Collected Addresses) from the old profile to the new.

Does this happen with the 78 release version? as earlier versions are no longer actively supported even if it is a bug it will not be fixed.

I found that this is a known program bug that can be easily fixed.

See: https://bugzilla.mozilla.org/show_bug.cgi?id=1608893

"Delete user_pref("offline.startup_state", 1); from prefs.js"