Where Does Firefox Store Session Restore Files

Yvette Bonnet updated Jul 08, 26

5 min(s)

TL;DR:

Firefox stores session restore files in the active profile folder, typically within the sessionstore-backups directory, and the exact root directory path can be found by entering about:profiles in the browser address bar.
    ● You must close Firefox completely before accessing or copying these files to prevent the browser from locking, updating, or overwriting the active session data.
    ● The recovery.jsonlz4 file contains the most recently active tab state, while previous.jsonlz4 holds the prior session data after a restart.
    ● Because .jsonlz4 files are compressed and tab data is saved per profile rather than per installation, always copy the entire profile folder to another location before attempting manual restores.

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Firefox stores session restore data in the active profile folder, usually inside a sessionstore-backups directory. Current and recent tab data may appear as recovery.jsonlz4, recovery.baklz4, previous.jsonlz4, or older sessionstore.jsonlz4 files.

The exact location depends on the operating system and the Firefox profile currently in use.

Step 1
Open Firefox and enter about:profiles in the address bar. Use it to find the active profile folder name and root directory instead of guessing from default paths.
Step 2
Close Firefox fully before checking the files. This helps prevent the sessionstore file from being locked, replaced, or updated while you are copying it.
Step 3
Open the active profile folder in File Explorer or Finder and look for sessionstore-backups. Check for recovery.jsonlz4, recovery.baklz4, previous.jsonlz4, and related session backup files.
Step 4
If no backup folder appears, check the main profile directory for sessionstore.jsonlz4 or older session files left from a previous Firefox version, crash, or profile migration.
Step 5
Copy any Firefox .jsonlz4 recovery files to another folder before testing restore attempts, editing profiles, refreshing Firefox, or reinstalling the browser.

Common Issues and Fixes

Tabs did not return after restart: likely cause is disabled session restore or a replaced session file; fix by checking sessionstore-backups for older files such as previous.jsonlz4.
Profile folder cannot be found: likely cause is Firefox using a different profile than expected; fix by verifying the active profile in about:profiles instead of searching only default folders.
Session file exists but tabs are missing: likely cause is Firefox saving a newer empty session; fix by comparing timestamps on recovery.baklz4, previous.jsonlz4, and other session files.
Session restore files are unreadable: likely cause is that .jsonlz4 files are compressed and not plain text; fix by keeping backup copies and avoiding manual editing unless the format is understood.
No session files remain after cleanup: likely cause is profile reset, manual deletion, or disk cleanup; fix by checking Recycle Bin, Trash, system backups, or file recovery options if deletion was recent.

Quick Tips

Firefox stores tabs per profile, not per installation. Multiple profiles can make the wrong folder look incomplete.
recovery.jsonlz4 usually reflects the latest open state, while previous.jsonlz4 may hold the prior session after a restart.
Firefox Sync does not always replace local session restore files. Synced tabs and local session data are separate in many cases.
Session files are small, so they can be overwritten quickly after deletion on an active system drive.
If file recovery matters, limit writes to the affected drive before scanning for deleted Firefox profile data.

💡Protip:

Copy the entire Firefox profile folder before experimenting with session restore. Keeping the original sessionstore-backups files untouched gives you more chances to test older .jsonlz4 versions without Firefox overwriting the remaining session data.