My suggestion is to download from the official site at https://www.thunderbird.net/en-US/thunderbird/all/

- on old PC, be sure to copy the ...appdata\roaming\thunderbird folder after shutting TB down. Otherwise, you get an incomplete copy

- Then, uninstall the MS version on new PC, and install the new version and then shut TB down. - Now, copy the saved thunderbird folder to the ...appdata\roaming folder - Restart TB and I think it will be okay.

Thanks David, I know the procedure and I know that if I download the install file directly from Mozilla, it will work perfectly. The case is that I HAVE TO use install from Microsoft Store (tl;dr company admin rights), that's why I look for help in this specific scenario.

Okay, but please follow the other steps carefully. What you described usually happens when the copy happens prior to the install, or where the profile was already compromised prior to the copy. I infer that you are copying from a windows pc to a windows pc, so the profiles.ini file in the thunderbird profile is there in the folder being copied, as that is what thunderbird reads to find the profile. That is, the thunderbird profile being copied must contain the profiles.ini file and the profiles folder with the profile intact.

What you described usually happens when the copy happens prior to the install, or where the profile was already compromised prior to the copy.

I'd thought so myself, if it wasn't done after the MS version was already installed. I didn't even run it, when I copied the files. I was actually pretty surprised when I was invited by the new configuration tab.

I infer that you are copying from a windows pc to a windows pc, so the profiles.ini file in the thunderbird profile is there in the folder being copied, as that is what thunderbird reads to find the profile. That is, the thunderbird profile being copied must contain the profiles.ini file and the profiles folder with the profile intact.

Sure, I've included profiles.ini with all other files in there. And I know that copying the data requires either to copy the file itself, or to edit it, so TB will look for the profile name as the folder's name indicates.

Unfortunately, the copying didn't work. That's when I created a new profile and I tried to edit, only to discover that the new profile's folder didn't even appear physically in AppData\Roaming location (!!!) I tried to override it by checking the new profile's name (in about:profiles) and renaming the old folder with its name. And... it didn't work as well.

That's why I tried coming here, because I feel like I ran out of options.

My conclusion is that, somehow, the MS store version is not actually using the AppData location, but some other, virtual location, explaining why despite the folder being configured, it didn't see anything I put there.

If nothing works, I know that the only thing left is to configure the new profile from scratch. What stops me is that I've been actually doing this recently, like 2 months ago, for different reason, and I really, really don't want to repeat it now.

Assuming Thunderbird is running with its default profile, you can determine location by clicking help>troubleshootinginformation, scroll down to 'profiles' and click 'open folder.' That will position you in Windows File Explorer in the profile itself and from there you will see the exact location. Also, assuming your saved profile is intact, you can import it and let Thunderbird position it by clicking tools>import>import from another thunderbird instalation and then select the actual profile within your copied folder.

The store version places the profile in a different location:

https://support.mozilla.org/en-US/questions/1434631

You should be able to copy the contents of a profile folder into the profile folder that is in the store location, just like you can when it's in the standard location of the non-store version.

Assuming Thunderbird is running with its default profile, you can determine location by clicking help>troubleshootinginformation, scroll down to 'profiles' and click 'open folder.' That will position you in Windows File Explorer in the profile itself and from there you will see the exact location. Also, assuming your saved profile is intact, you can import it and let Thunderbird position it by clicking tools>import>import from another thunderbird instalation and then select the actual profile within your copied folder.

Yes, I did it all, in 'about:profiles' I get whole file path leading me to AppData\Roaming location and the folder named after the new profile's name, but when I used the link to go there I simply got error that the path doesn't exist. Same with going there manually - it simply doesn't exist.

The store version places the profile in a different location: https://support.mozilla.org/en-US/questions/1434631 You should be able to copy the contents of a profile folder into the profile folder that is in the store location, just like you can when it's in the standard location of the non-store version.

YES!!! I felt that the issue is caused by some weird, different place to store all files.

I checked and there it is: C:\Users\username\AppData\Local\Packages\MozillaThunderbird.MZLA_h5892qc0xkpca\LocalCache\Roaming\Thunderbird - the folder with the new profile I created.

I will later try to copy the old profile's files and see how it works, but apparently it should fix the case now.

Great thanks, mate !!!

I don't have a machine to test, but once you copy the files in and having it running, can you clear the cache in Thunderbird user interface and ensure that the profile does not just go to god. I am very hesitant about storing permanent data (profile) in a location with caching in it's name.

I do find it rather sad Mozilla have not fixed the bug in the about: troubleshooting information on a year so the product can actually tell you where the profile is. It might be a reflection on Firefox's market share.