How to read sessionstore-backups files

User Help for Mozilla Firefox

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Posts: 24
Joined: November 25th, 2005, 9:05 am
Location: Montreal, Canada

Post Posted September 28th, 2019, 6:54 am

The sessionstore-backups files content look compressed and seeing their file extension end with "lz4" I did a quick search and found out LZ4 is a compression format. So I downloaded its program and tried to decompress them all but got the error
Error 44 : Unrecognized header : file cannot be decoded
for each. I'm assuming FF customized it; if so, how can I standardize it so LZ4 decompress it? Or how can I get to view their content?

Thank you kindly
Je suis francophone. My main language is French.

Posts: 511
Joined: January 30th, 2019, 9:38 am

Post Posted September 28th, 2019, 7:09 am

Sometimes the files can be put back into the profile to open those tabs in the browser - ... om_backup/
If this does not work or you prefer to just see the links, this usually will help -


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Joined: March 10th, 2004, 9:59 pm
Location: Maryland USA

Post Posted September 29th, 2019, 7:16 am

Like much of what Mozilla does, it's usage of .lz4 is "non-standard", so not all lz4 utilities will work correctly with "Mozilla lz4" files.

This one does (Windows),

This was also pointed out, though I have not used it, ... zlz4-edit/.
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv: Gecko/20110420 SeaMonkey/2.0.14 Pinball CopyURL+ FetchTextURL FlashGot NoScript

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