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Update of Firefox will no longer open

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  • 1 has this problem
  • Last reply by jscher2000

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I use firefox on the server at work. A lot of bookmarks are there for sites I have to go to for work. When Firefox updated, I can no longer open Firefox. I get an error message saying that I can't open the older version because it can corrupt some bookmarks and instead it says to make a new profile, but the other one has all of my data. I didn't sign in with my personal Firefox, so I have no idea how to get the bookmarks back. Any help is appreciated.


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Hi Judson, Firefox 67+ won't run a profile that has been upgraded by a later version. Can you think of any reason the profile might have been touched by a later version of Firefox than the one you are running??

If not, perhaps there is an error in the compatibility.ini file in your regular profile. I don't know whether it is safe to edit or delete that file, but in case you want to try either of those steps, you can do it this way:

(1) Open the about:profiles page (type or paste that address in the address bar and press Enter to load it)

(2) Find your older profile on the page and click the Open Folder button for the "Root directory"

(3) Right-click the compatibility.ini file and Rename to compatibilityOLD.ini then press Enter to complete the edit

(4) Back on the about:profiles page, click the "Launch profile in new window" for your older profile

  • If Firefox will launch the profile (not demanding a new one), then check the data integrity to see whether your data is still the way you remember.
  • If all is good, switch over to the about:profiles page and click "Set as default profile" for your older profile. Then you can close out of that window and you're back in business.

If it doesn't go as hoped, well, you can copy the older files from the bookmarkbackups folder in your older profile folder to the same folder in your newer profile folder. Then: Restore bookmarks from backup or move them to another computer.