You are seeing that message because the profile is pointing to a profile that isn't there. This is a setting in c:\users\(yourID)\appdata\roaming\thunderbird\profiles.ini. If you know the location of profile, just update this txt file and TB will run properly. Unless you moved it, the profile is probably at c:\users\(yourID)\appdata\roaming\thunderbird\profiles\xxxxx.default (or similar). If true, just type that in on the path statement.

There is a profile (xq99hdlo.default) located in the Profiles folder. The Profiles.ini contains the following: [Install8216C80C92C4E828] Default=Profiles/xq99hdlo.default

[InstallD78BF5DD33499EC2] Default=Profiles/epdcmpjy.default-release Locked=1

[Profile1] Name=default-release IsRelative=1 Path=Profiles/epdcmpjy.default-release

[Profile0] Name=default IsRelative=1 Path=Profiles/xq99hdlo.default Default=1

[General] StartWithLastProfile=1 Version=2

So I'm not sure what to do with the INI file or Profile file at this point to fix the problem. Do I change the name of the Profile file or change the information in the Profiles.ini? Or do I have to move the Profile file to a different location?

I would set all names in profiles.ini to the xq99dhlo.default TB will start if the profiles.ini points to a good profile. Let me know how it goes.

Interesting..... I had been trying to install Thunderbird Setup 91.6.2 Today I downloaded Thunderbird Setup 91.7.0 and it installed without issue. Could it be that the 91.6.2 version had a problem that wasn't mentioned? And it was fixed in 91.7.0? It sure would be nice if there was SOME support from Mozilla itself instead of relying on all us users to get problems fixed.

Thanks to David for his insights and help.

Thank you for your kind words. i'm glad the issue is resolved. What you encountered was a very rare situation, never reported by anyone else. I share your wishes, but this is a volunteer organization, so this forum is the place to go. Unfortunately (in my opinion), most problems seem to be created by anti-virus programs that get entangled during upgrades. And that may have been part of your issue. Hard to know. Thanks again.