That only works if the version of TB on the source PC is exactly the same as on the target PC. The TB 91 has created a new profile that is like a new install. Close TB, delete the contents of the new profile folder (not the folder itself) and copy in the contents (not the folder itself) of the source profile folder. Then start 91 and see if your data appear.

But if the source PC was not running TB 91, I would recommend not copying in the entire profile contents, but building the new 91 profile by adding accounts and transferring mail, address books etc. separately from the source profile.

sfhowes, Thanks for reply. Reinstalled TB91 on source computer, post upgrade target PC email accounts installed as expected. Was good advice thx.

Unfortunately calendar (Google) did not make the cut. Calendar email address is there & have enabled but no entries .. Have any ideas restoring function.

There are many users reporting the calendar is missing after the update. If you were using the Provider add-on, disable or remove it, then add the calendar directly as a CalDAV calendar:

https://support.mozilla.org/en-US/questions/1304356#answer-1368791

https://github.com/kewisch/gdata-provider/issues/194

Disabled provider deleted & reinstalled. calendar. Hit the ground running. Thank you.