Profile compatibility between Thunderbird versions ?

I seem to recall reading a while back that old Thunderbird profiles may not be compatible with newer versions of Thunderbird, or vice versa. IOW I may not be able to use my old Tbird profiles from my Windows 10 sdd with a newer version of Tbird that will get installed onto a new sdd with a fresh copy of Windows 11. Or is that wrong information?

The profiles are on my D: drive, and the Profiles.ini folder on the C: drive points to the D: drive. Is it safe to presume that I just need to copy the modified Profiles.ini into the new installation?

That is correct. I have Thunderbird on three computers, my primary, backup, and my laptop. My main computer automatically updates TB whenever a new version comes out. If I copy my profile over to one of the usually dormant computers and just run with a slightly older version, TB complains that my profile is from a later version.

I just download the latest TB install file and do an install before I try to open TB on my secondary computers. The TB install automatically does an update if a previous installation is present, so it's a pretty painless operation.

To update my profiles on the secondary systems, I just copy the entire profile from my data drive. Note that you should NOT be running TB anytime you're copying the TB profile.

Thanks,

So if I update to Thunderbird 128 or 144 on my Windows 10 C: drive it's possible this could update/modify the profiles on my D: drive.

If that occurs, what happens if I restore the C: with an image containing Thunderbird 115 or earlier? Could the profiles become useless?

I do have a backup copy of the profiles so could always restore Windows 10 in full working order. I just like to know what I’m working with in case things don't work out.

Chuck99 said:

Thanks,

So if I update to Thunderbird 128 or 144 on my Windows 10 C: drive it's possible this could update/modify the profiles on my D: drive.

If that occurs, what happens if I restore the C: with an image containing Thunderbird 115 or earlier? Could the profiles become useless?

I do have a backup copy of the profiles so could always restore Windows 10 in full working order. I just like to know what I’m working with in case things don't work out.

Click to expand...

No, it will NOT modify your profiles on the C: or D: drive. However, when you run with a specific version of Thunderbird, the profile does get "marked" as being linked to that version. You can't move it to an older TB version and expect it to run. However, it will automatically be updated if you run it with a newer version of TB. The

FWIW, I regularly backup my TB profile that I have on my data drive in case if issues.

The profiles.ini in my User folder on the C: drive just points to the profile on my D: drive. I have a Thunderbird folder in the root of the D: drive with my actual profile.

I'm sure several of the entries could be removed, but I figured I'd let TB have it's bloat.

It is just like Firefox.
All you have to do is delete the compatibility.ini file in your profile folder of Thunderbird or Firefox as that is what contains what version of Thunderbird or Firefox you are running.
It will be recreated the next time you run the program.

KevTech said:

It is just like Firefox.
All you have to do is delete the compatibility.ini file in your profile folder of Thunderbird or Firefox as that is what contains what version of Thunderbird or Firefox you are running.
It will be recreated the next time you run the program.

Click to expand...

Learned something today, never realized that file existed.

Thanks for all the information & the tip about deleting the compatibility.ini. That saved my butt.

Short version - I made a disc image of the C: drive & then updated Thunderbird & Firefox. I used both afterwards, before making copies of their profile folders that were on the D: drive. That was a mistake.

Later on I restored the C : image which was only a couple days old. I have a few TB profiles and the compatibility.ini file did not change on the D: drive for two of them because they were not used after TB was updated. But two did change because they were accessed. I renamed the compatibility file instead of deleting it and it took a few seconds for TB recover or whatever it had to do and got things working.

Firefox’s compatibility.ini file did not match either. Renaming the file worked, but it took a minute or so for FF to start working. I wondered if this was going work because it took so long & eventually it did.

Lesson learned. The D: profile folders should be copied when the C: image is created in order for the compatibility.ini file to match the software version. That should eliminate any problem if you want to restore the C: drive to an earlier version.

I moved the compatibility.ini file and restarted Thunderbird, it didn't seem to take any more time than normal to start and the file magically appeared again. The file contents look identical to the one I moved.