I don't understand your statement beyond the update changing your profile. All updates change your profile.

So what version were your using and what happened when you updated? Could it be a new profile was created and you were initially asked for your email address and password?

Hi Matt, I was on 115.13 and did the update to 128.01 esr. It updated and then restarted. When it restarted, all of my accounts were gone along with my address book was gone as well. Thunderbird asked me to create an account. I recreated one my accounts hoping that it would pick up the other 5 accounts, it did not. So since I did not like look and feel of the new version, I uninstalled it and went back to 115.13, again hoping to get my accounts back. That is when I got a message saying this profile is for a newer version. I wasn't aware that Thunderbird changes the profile(s) in a way that makes it not backwards compatible. Now being aware of that If I ever decide to update again, I will make a copy of my profile(s) to save the info and make it easier to recoup my data. I have been using FireFox and Thunderbird since the very beginning. However I don't think I will be updating Thunderbird. I did not use 128.01 very long, however It seems that Thunderbird is going in a direction that does not appeal to me. Thunderbird is trying to be a everything program, Chat, Calendar and Email. I do not use the chat feature. Again I didn't use it long, I found it too busy and trying to push the calendar and chat features, just MHO.