I have been having a small but irritating problem with Thunderbird.

I use the Nightly (Firebird) version which is currently V21, but I believe this problem is not new.

Whenever I opened Thunderbird, it insisted on opening three or more versions of itself, which meant closing several windows every time.  It started off with three windows, but over time this grew to seven which meant a tiresome session of closing windows each time.

I searched the Internet and this is not a new problem.  The answer generally given is to close the extra windows using Alt+F4 but this didn’t work for me.  It closed the windows all right, but the next time I ran Thunderbird the problem was still there.

The solution is simple.

Delete the file “session.json”.

For the uninitiated, open your file browser and ensure that “View –> Show hidden files” is selected.

Browse to home/.thunderbird (note – dot thunderbird!) and you will find “session.json” in your default profile folder.  If for any reason you have several profile folders, the active one is listed in the file “profiles.ini”.

Well, it worked for me…….