Been using Thunderbird for years.. Till my other computer Quit (Month ago), Thunderbird had been working fine. Had been using 32 bit version, on 64 bit Windows 8.1 computer. Saved a copy of my Working Profile on external hard-drive. Got a New pc, Windows 11, also 64 bit. Downloaded Thunderbird. Got a 102.3 (?) 64bit version. Installed. Tried to put a Compuserve e-mail account in. Compuserve comes off Aol.com. (pop.aol.com). I put my info in. An Aol window comes up with my address and a NEXT key in window. Thunderbird is "Checking password". Checking password..... Checking Password.... I click on Next. Put in my Password.. Incorrect password. I quit out. Go to Compuserve Mail, thru Firefox. Log-in successful with Same password... Hmm.... 3rd part App Password create??? I go to Aol Security page... Put in Thunderbird (note there about previously created App pw). Create Another. Go back to Thunderbird.... Or TRY. "Invalid or missing Profile". Uninstalled/reinstalled Thunderbird. SAME problem. I went back, and downloaded the 32bit version of Thunderbird. SAME Problem. After looking at a couple of online Thunderbird site messages, I went to my .../appdata/roaming/thunderbird/profiles. I renamed the profile.default with profile.default_old. Renamed two .ini files to .old. Reinstalled 64bit version. Was able to Run Thunderbird again, but STILL wouldn't connect to Compuserve. WAS able to connect to Gmail account. Tried going into settings. Found SAVED PASSWORDS. Saw Full sign-in password was there. Changed it to the Aol App password. Same problem. Hmmmm... At some point, I was able to IMPORT from my Previous Profile (created with 32bit TB, on Win 8.1 64bit pc). SAME problem connecting to Compuserve email. Why did IMPORTING Change the Modified Date of the ORIGINAL Profile file??? I am also trying to change my Profile location, from an SSD to my Terabyte hd. Saw something about changing the Local File destination, in settings.. Did that. Thunderbird restarted. NO change, except that the "Local Files" listing, in the Folders listing, now had a LOCK on that Profile. I tried to change File Location for my Compuserve folder, but, was told it was In-Use by Local Files. There was Nothing in the Heading Folder for my Compuserve email folders to set them ALL to another Profile file. There was an Option in EACH (sub-folder) to set the Profile Folder Location. As I said, above, I have been using Thunderbird, for Years, and would hate to have to get to Another email program, and RE-folder all my mail together (sorted by user, org, service, etc). My E-mail service is Still "up there" with my mail. Wonder if I could try to Repair my old drive, and grab program files from there. (Where is that Usb to Sata converter???) If I was able to get Thunderbird 32bit program files (with my Working settings), I could probably use them, as I had been. What would happen if I then installed the 64bit version, over that? Hopefully, I gave enough of an idea of what I tried.