Once you have the thunderbird folder, created when thunderbird is NOT running on old pc, you need to: - install thunderbird on new pc and then exit. - copy the thunderbird folder to c:\users\<yourid>\appdata\roaming that will prompt to overwrite. Allow it. - start thunderbird

Thanks much, David. That worked.

The https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer instructions I used told me (step 5, destination computer) to 'Open (profile) Folder', then close Thunderbird, en then from the Thunderbird profile folder to go three levels up. Doing that got me to the (hidden) 'Thunderbird' folder, and not to the 'Roaming' folder one level higher. Clearly, the online instructions were not an clear/correct as what you told me. Perhaps Mozilla could update/clarify its instructions?

Anyway, I hope your answer will also be of use to others facing the same difficulty.

You're welcome, and thank you for your feedback. I post those instructions probably twice a day. I agree with your assessment; I have always had trouble with wording to back up three levels. I think the intent in the wording is that many users are unable to work with Windows File Explorer, so the instructions have to work with that restriction.