Posted on Linux Mint forums - no response yet!
I'm having difficulty upgrading Thunderbird (and also Firefox to some extent) and not loosing my profile, emails and calendar. There seems to be no recent information on this topic with regards to upgrade proceedures. I've upgraded to Mint Cinnamon and replaced the Thunderbird profile including the "profiles.ini" file. Now, when I try to open Thunderbird, it tells me that another copy of Thunderbird is already running, and that I must first close the open version and/or reboot. After rebooting I continue to receive the same message; and so can't use Thunderbird. I've uninstalled and reinstalled Thunderbird with my old profile in place... I need to edit something to tell Thunderbird it is closed, so I can open it. Please help... and include the proper information in the current (really good) upgrade instructions for Firefox and Tbird.