Preliminary Checks

• I have read and understood the important section above.
• I have searched existing issues and avoided creating duplicates.
• I am not filing an enhancement request.
• I have checked that this issue cannot be reproduced on Mozilla Firefox.
• I have checked that this issue can be reproduced once I removed all my Mods and Custom CSS.

What happened?

I don't exactly know when it happened in the past 24h, but I realized today that the tabs on all my spaces are missing. Diving more deeply, everything was missing except:

• the spaces themselves
• the pinned tabs in spaces
• the pinned folders (and their tabs) in spaces)

No problem, I thought. I'll just recover a backup. I tried to follow the steps to recover my tabs using the steps from your docs: link, however after copying over .zen/<profile>/zen-sessions-backup/zen-sessions-2026-06-16-15.jsonlz4 to .zen/<profile>/zen-sessions.jsonlz4, the tabs were still missing.

To be sure that the backup contained my tabs, I extracted the JSON from the backup jsonlz4 file and looking through the data, my tabs are still all there, so the file seems to be correct. IntelliJ didn't see any JSON syntax errors either.

Expected behavior

My tabs are restored after following the guide in the Zen docs

Actual behavior

Only my spaces, pinned tabs and pinned folders are there

Steps to reproduce

1. Close Zen
2. Go to .var/app/app.zen_browser.zen/.zen/9przbrus.Default (release)/
3. Move zen-sessions.jsonlz4 to zen-sessions.jsonlz4.bak
4. Copy zen-sessions-backup/zen-sessions-2026-06-16-15.jsonlz4 to zen-sessions.jsonlz4
5. Open Zen

Screenshots and videos

No response

Version

1.21.1b

What platform are you seeing the problem on?

Linux (Flatpak)

What component is this issue related to?

Tabs

Relevant log output if applicable

ZenSessionManager: Initializing session manager ZenSessionManager.sys.mjs:121:15
ZenSessionManager: Session file path: /home/rik/.zen/9przbrus.Default (release)/zen-sessions.jsonlz4 ZenSessionManager.sys.mjs:121:15
ZenSessionManager: Reading Zen session file from disk ZenSessionManager.sys.mjs:121:15
ZenSessionManager: Restoring only pinned tabs into windows ZenSessionManager.sys.mjs:121:15
ZenSessionManager: Restoring Zen session data into 2 windows ZenSessionManager.sys.mjs:121:15
ZenSessionManager: Restored sidebar data into window 
Object { tabs: 35, groups: 5, folders: 5, spaces: 11 }
ZenSessionManager.sys.mjs:121:15
ZenSessionManager: Restored sidebar data into window 
Object { tabs: 35, groups: 5, folders: 5, spaces: 11 }
ZenSessionManager.sys.mjs:121:15