Thunderbird stores preferences like sort order in a file called session.json in the profile folder.

Issues can occur if this file becomes corrupt, or third party software interferes, or deletes the file (ccleaner did this for many years)

SO initially I suggest you try deleting the file ( a new one will be created) and see if it fixes the issue. If not thien it is time to look for that third party software.

Open the profile Folder by clicking the show button in Troubleshooting information on the help menu. Then shut down Thunderbird Then delete the file Then restart Thunderbird.

You will find a number of user interface options revert to default, like showing the reading pane for email.

I followed your advice and deleted the file session.json It seemed to work for a few days before regressing. I repeated the process and it has worked fine for over two weeks so I am counting that as successful. Thank you for your help KD

The session.json file contains the list of tabs that were open when TB was last closed, as well as some other items, such as Quick Filter Bar and pane layout. You can view it with a text editor. It does not contain anything to do with the column selections or whether the list is ordered by ascending or descending date. This information is in the .msf index files assigned to each folder. If you rebuild the index files from the folder right-click menu, Properties, Repair Folder, the columns will be reset to default values, but after you reorganize the columns, the settings should be retained between TB restarts.

I have a similar issue in that recently (say for the last five or so months) TB has stopped loading with the last tabs. It does not matter how many open tabs I have left when I log off. The only two that reload when I start again are two accounts which are pop3, but it will not load my exchange account (accessed with Exquilla). It never had a problem with Exquilla previously. I have followed the advice about deleting session.json, which I have done numerous times but with no solution to this issued. This issue occurs on ALL of my machines running with TB. Why is this really frustrating issue happening?

It would help if you could find if this due to an issue with your profile or with Exquilla. Create a new profile from Help/Troubleshooting, about:profiles, install Exquilla, add an Exchange account, and see if the open tabs are restored after restart. If they aren't, it is almost definitely an Exquilla bug, which you can bring to the attention of the add-on author.

Hello and thank you for the quick reply. I have followed your suggestions about making a new profile and so forth. The issue does appear to be with Exquilla, though I also tried using Owl Exchange, too, and the same issue occurred. The exchange accounts do not show up on the tab. The pop and imap accounts load at the start as they should. While you may be right that the issue is with Exquilla, there might also be an issue with TB. I did notice that in the session.sjon file, the first tab field for the exchange account was set to "false." I changed it to "true," but it did not make any difference.

Thank for your help. cbergs