I keep my profile on a detachable USD hard drive so I can use Thunderbird on my laptop when I travel just as I do on my desktop. Thunderbird on both of these computers is the 32-bit version and kept up to date (version 115.6.1). I know how to point Thunderbird to use the profile on the USB drive via the profiles.ini configuration. Recently, I bought a new desktop computer and downloaded Thunderbird from the download web page. UNBEKNOWNST TO ME it downloaded the 64-bit version without giving me a notice or a choice. I edited the profile.ini file to point to the profile on the USB drive and it did not work well. The calendars were disabled, no mail folders appeared and no email accounts appeared. My contacts were OK. So, I shut down the new desktop and I put the USB drive in my old desktop, ran the 32-bit Thunderbird and it now looked as dysfunctional as it did on 64-bit Thunderbird. Ooof. Dead in the water. Fortunately I had a 2-month old backup and restored that profile after renaming the damaged profile folder on the USB hard drive. I then copied over the mail folders from the damaged folder to the restored profile folder so I would have all the latest mail. I also copied over any files in the main folder of the damaged profile that had not been changed by the 64-bit program on the new desktop computer. Fortunately, when I ran 32-bit Thunderbird, all my email from the last 2 months was there. Some recent calendar entries were missing and I had to redo the POP protocol for one of my 5 email accounts I manage with Thunderbird as I did a couple weeks ago. Yay! I immediately backed up the USB hard drive. So, any clue why this happened? I am planning to make a test on the new desktop. I uninstalled the 64-bit version and installed the 32-bit version. I am going to restore the 32-bit profile folder from the backup to a USB stick with just the profile folder to see if it works as it does on my old desktop and laptop by just editing profile.ini (and installs.ini) as it is on those two systems.