More information may help. the active profile prior to update should still be available. Click help>troubleshootinginformation, scroll to 'profiles' and click 'about:profiles', then see if more than one profile is shown. Launch and see if your data are there. Regarding the backup, I suggest viewing the backup via Windows File Explorer to verify that the missing folders are there, as sometimes a backup is itself incomplete.

Hi, Thanks for the response.

Current profiles are: default-release ********6l.default -release default ********30k2.default default-release-1 *********l5i default-release-1

I have last months copies of 6l and l5i on a hard drive. If I copy those over to Drive C: will I get all the folders back? Alternatively, if I create a new profile (as prompted by TB) can I copy all old folders to the new profile?

Yes, if you have a profile with all the needed folders, restoring that folder will work. But I do suggest verifying that the follders are there.

David, should simoncharlestomsett have to restore profiles from a back-up copy? Thunderbird created a new profile because the existing one may be incompatible with the new version of Thunderbird. The old profiles are still in the profiles folder. What is the best way to access an old profile without risking incompatibility?

I know that sometimes it seems safe to delete the compatibility.ini file in an old profile and set that profile as the default, but I don't know when it is safe and when it is not. Should simoncharlestomsett copy mbox files from the old profile that is still in the profiles folder to the new profile?

My experience is all I can go on. Going from a recent release to the newest release causes no incompatibilities. Going backwards sometimes works, but only with compatibility.ini file deleted. Thunderbird's rejection of current profile doesn't mean a problem; it just sometimes starts fresh. That can be frustrating because it leaves user wondering about lost messages and contact list. My preference is to restore the old profile, after first verifying that it is complete. That eliminates the issue of missing folders. Copying mbox files always works, but can be messy with POP accounts, as it can impact the 'last message downloaded' status.

I managed to install an old profile eventually, though it took a long time to find somewhere that TB would allow me to save it. After default release-1, I used Mail\Local and it works. Now my only problem is that JPEG attachments don't open, though PNGs do. I've got Original HTML actioned. Defaults are set to Fastone Image Viewer. Right click shows options but "open" doesn't work. Any ideas?

I managed to install an old profile eventually, though it took a long time to find somewhere that TB would allow me to save it. After default release-1, I used Mail\Local and it works. Now my only problem is that JPEG attachments don't open, though PNGs do. I've got Original HTML actioned. Defaults are set to Fastone Image Viewer. Right click shows options but "open" doesn't work. Any ideas?

Would you please start a new discussion with that issue so more people will see it and might respond?