Thunderbird reports Trash folder is full, so I cannot delete messages from Inbox.
I moved or deleted thousands of emails from the Trash folder and compacted. Still no luck. Upgraded to Win 10 last week. Have Thunderbird 45.2.0.
Alla svar (7)
right click the folder, select properties... what is the size on disk.
Not sure if I correctly posted my reply. Size is 6.2GB
I'd suggest you open your profile, find the large Trash file and then delete or rename it. That will force Thunderbird to create a new one. Note that a folder in Thunderbird is represented by a file in your file manager.
However if the account uses IMAP it may well repopulate the local Trash folder from the server copy. I think, given that mbox files are simple text files, you could create a new empty file named Trash, to replace the one just deleted or renamed, and Thunderbird will see it, see that it is empty and tell the server to delete its own copies of the messages. You can use Notepad to create this file, or the tools in Explorer for creating a new text file. Both methods will almost certainly add a .txt extension which you must remove by renaming it. Whilst about it, I'd also delete the accompanying Trash.msf file.
The easiest way to find your profile is to go to Help|Troubleshooting Information in Thunderbird. The page that appears has a button near the top that will open the profile folder in your file manager. Close Thunderbird before doing any surgery on the profile.
Zenos. That worked great. I renamed the trash file and the trash.msf file. Thunderbird created a new trash file and I'm back in business. Thank you.
Yay!
Was it POP or IMAP? I take it that you didn't need to create a new empty Trash file?
POP. I renamed Trash to Trash 1 because I wanted to retain many of the deleted messages. Trash 1 still appears in my subfolders and is searchable. Thunderbird created the new empty Trash file. I'm back on solid foods :-)