End Thunderbird's process via Task Manager then start the profile manager and create a fresh blank profile. You can then restore the June 5 backup and see if Thunderbird remain stable. I would love to know exactly what happens when you get that error? Are you trying to run another instance of Thunderbird when it's already running? Does Thunderbird crash or disappear abruptly from your display?

Hi Stans Thank you for the feedback. I only get a pop up with that error message. I cannot get Thunderbird to start at all on the old laptop. On both old and new, Thunderbird has not been running in Task Manager when/or just after I get those messages.

On a fresh install on new laptop, I can get a clean instance of Thunderbird to install. As soon as I attach my recent profile backup via Profile Manager or by replacing the full Thunderbird directory with my backed up copy - the errors start on the new computer and I cannot open Thunderbird program again.

My thought overnight is I still have the Laptop #1 that I have to send back to Lenovo soon - and it has an uncorrupted 5/29/2020 version of Thunderbird in the Roaming directory. That is the last version before I installed Thunderbird on the Laptop #2 (old laptop) successfully on 5/29/20. I have not started Thunderbird on Laptop #1 since I moved to Laptop #2. My thought is to install this 5/29/20 backup on Laptop #3 (new laptop) in exactly the same manner as I did on 5/29/20 to old laptop #2.

I think I need to 1) uninstall Thunderbird on new laptop #3 and erase the Thunderbird directory under Roaming 2) do a fresh install of Thunderbird on new laptop #3 3) copy the 5/29/20 Thunderbird backup to just under the Roaming directory on top of the fresh install This is what I did on 5/29/2020 with beautiful success. I did not even know that the Profile Manager existed at that time - and am not having the best luck with it right now.

Another thought...is there any way to change the profile name and use my latest backups if this persists? Would it involve only changing the profile file name in windows to NEWNAME.default or something like that, then alter the profiles.ini in Notepad? Seems too easy?!?

See Profile in use

Thank you christ1....I had been through all of the steps regarding "Profile in Use" before making the original post - I will go through that again.

First, I will do one of two things now. Try to install on the newest computer from the set of files that I used on 5/29/2020 - and try to do it in exactly the same way as I reinstalled on Laptop #2.

If that does not work, I will try to open Thunderbird on Laptop #1 that was last used on 5/29/2020 - the place where this copy came from. I have not opened Thunderbird on that computer since making the copy that I have. Am nervous about opening it there.

If anyone has any precautions regarding those two steps -- please let me know.

On the new laptop, with a fresh install of Thunderbird, and using the method that worked last time - copy last used Thunderbird directory to newly installed Thunderbird directory - worked!! I used the 5/29/2020 copy that I had. All of the e-mails since that date came flowing in and I am only missing the e-mails SENT since then. I can live with that.

I appreciate the help from you all. cheers

If anyone has any precautions regarding those two steps -- please let me know.

One word; backup, backup, backup! It cannot be stressed enough. Always make a backup copy of a profile and keep it somewhere convenient, before trying various things on the one in use by Tbird. Do this and you won't have any fears or uncertainities. If something breaks in the process, it's a simple matter of purging the broken profile and restoring a copy of the backup. Always Quit Thunderbird before copying, moving or modifying anything in a profile folder.

Great advice Stans...and I will definitely be more diligent backing up more often. I feel so fortunate that I had one less than a month old - that was unusual based on my old processes. I got lucky.