Firefox 153.0.3 does not save session when Firefox is closed

Firefox 153.0.3 does not save session when Firefox is closed Since the latest Firefox update, Firefox no longer restores my open tabs after closing and restarting the browser. This worked correctly before the recent Firefox update; the problem appeared immediately after updating Firefox. Firefox version: 153.0.3 (64-bit) Operating system: Windows 11 My Firefox startup setting is enabled: Open previous windows and tabs However, this setting no longer works. Steps to reproduce Start Firefox normally. Open several websites in separate tabs (I tested with 3–5 tabs). Close Firefox normally using the Firefox menu / Exit. Start Firefox again. Actual result All previously open tabs are gone. They are also NOT available under: History → Recently Closed Tabs There is no usable previous session to restore. Troubleshooting I repeated the same test in Firefox Troubleshoot Mode, with the same result. Therefore this does not appear to be caused by an extension. Session files I checked the Firefox profile's sessionstore-backups folder. The folder contains, among others: previous.jsonlz4 recovery.jsonlz4 recovery.baklz4 several upgrade.jsonlz4-... files After testing with several open tabs, the current recovery.jsonlz4 and recovery.baklz4 files were only about 2.4 KB in size. This suggests that Firefox is not correctly saving the current browsing session when it is closed. The problem started after a recent Firefox update. Before that update, session restore worked normally. I would appreciate it if this could be investigated as a possible Session Restore regression in Firefox 153.0.3.