Select Help/Troubleshooting Information, click Open Folder, close TB, delete or rename session.json. Restart and close TB a few times and see if the tabs that were open at closing are open when you restart.

This procedure was run a number of times. Initially, I discovered that the Calendar tab does return, but it is placed at the far right of the collection of tabs - I want it as the second in the list of tabs, as was in the previous version.

Side issue discovered. When "File-Close" is used to close the application, it appears the session.json file is updated. If the "X" in the upper right corner of the application is used, the file is not updated - I had numerous restarts with only the Inbox showing before I tried the File-Close method.

Images of the desktop showing Thunderbird and the >>> C:\Users\rogya_7pa42dv\AppData\Roaming\Thunderbird\Profiles\855hleqn.default <<< folder, and the several session files that were created.

Request further assistance.

Thanks!

Roger Yaeger

Tabs can be rearranged by drag and drop, and the order of tabs is retained here upon restart.

Closing TB from the File menu or the X icon both force an update of session.json here on my setup. I never see more than one version of session.json, which suggests that on your system some process is interfering with writing the file at exit, perhaps CCleaner or antivirus.

Tabs can be rearranged by drag and drop, and the order of tabs is retained here upon restart. <<<your comment. The tabs stay in the order at closing, EXCEPT the Calendar tab returns to the FAR RIGHT SIDE - not at the #2 spot where it was left immediately to the right of the Inbox. This is the problem I am asking to be solved. </p>

Closing TB from the File menu or the X icon both force an update of session.json here on my setup. I never see more than one version of session.json, which suggests that on your system some process is interfering with writing the file at exit, perhaps CCleaner or antivirus. <<< Your comment. I see only one copy of the session.json -- I have renamed each old file to preserve it on my system. The point I was raising was that if tabs are present, the file session.json is renamed, closing with the "X" doesn't review the present tabs that are open before closing, which means that at restart only the Inbox tab is present - ALL previous tabs, including the calendar are missing.

Problem still not resolved.

Thank you,

Roger Yaeger