You do not. It is what it is. a few kilobytes for you but not for the people that run 100 to 400 open tabs at a time. If you need to repair it this maybe useful : https://www.jeffersonscher.com/res/scrounger_json.html

Pkshadow said

You do not. It is what it is. a few kilobytes for you but not for the people that run 100 to 400 open tabs at a time. If you need to repair it this maybe useful : https://www.jeffersonscher.com/res/scrounger_json.html

I also often have 200 tabs opened. How much is lz4 supposed to save?

I wanted to recover a session file using a plain text editor, but lz4 prevented me from doing that.

How do I bypass lz4 and rescue my session?

Please use a copy of your file in the the above URL. You have not said that you have so please do so.

Only work on the Profile when Firefox is closed. Use copies only, never work with original files.

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
• https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks
• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox
• https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them
• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

What's What in the Profile

• bookmarks and history: places.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (passwords) and key4.db (58+) or key3.db (57 and older) (decryption key) for Passwords saved in the Password Manager
• if you only have key3.db then make sure to remove an existing key4.db
• cert9.db (58+) or cert8.db (57 and older) for (intermediate) certificates stored in the Certificate Manager
• if you only have cert8.db then make sure to remove an existing cert9.db
• persdict.dat for words you added to the spelling checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

Pkshadow said

Only work on the Profile when Firefox is closed. Use copies only, never work with original files.

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
• https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks
• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox
• https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them
• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

What's What in the Profile

• bookmarks and history: places.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (passwords) and key4.db (58+) or key3.db (57 and older) (decryption key) for Passwords saved in the Password Manager
• if you only have key3.db then make sure to remove an existing key4.db
• cert9.db (58+) or cert8.db (57 and older) for (intermediate) certificates stored in the Certificate Manager
• if you only have cert8.db then make sure to remove an existing cert9.db
• persdict.dat for words you added to the spelling checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

I see. Now, what is the advantage of lz4? What was wrong with plain text?

We're not developer types; this forum is "staffed" primarily by other Firefox users. Ans the occasional Mozilla developer who wanders in here usually answers to support questions, not inquiries as to "why" something is does in the manner that Mozilla does things. No need to justify, defend, or explain development decisions.

Overall, what difference does it make as to what the advantage it. Firefox is made to use that file type and Mozilla developers aren't going to change it or provide a decompression utility.