re :I've gone through the suggested process for transferring my thunderbird

Please tell forum exactly what you did. What was the OS of the old computer? What is the OS of the new computer ?

Did you do this: Assuming both the old and the new computer are Windows OS.

Exit Thunderbird on both computers - this is important.

On old computer: Access profile located here: C:\Users\<Windows user name>\AppData\Roaming\Thunderbird Copy the 'Thunderbird' folder

On new computer: Access profile located here: C:\Users\<Windows user name>\AppData\Roaming\Thunderbird Delete the default 'Thunderbird' folder

Paste your copied 'Thunderbird' folder (from old computer) into the 'Roaming' folder. Then start Thunderbird.

Ok, that worked and solved my problem. I now have my folders, address book, etc. The missing step which seemed to solve the problem is on the destination computer one must delete the default Thunderbird folder before pasting the Thunderbird folder from the transfer drive. If you look at the instructions on the Mozilla support page, on step 12 and 13 say to copy and paste the transferred file and then opt to replace data when prompted. I tried that 4 times and it never worked. After reading the above solution, I deleted the default folder first and then pasted the transfer file and bingo! It worked. Thank you for saving me from further frustration. Someone might want to add that important step to the instructions and the Youtube video.