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Can't open Firefox because a copy of Firefox is already open

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  • 0 有這個問題
  • 7 次檢視
  • 最近回覆由 cor-el

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I use a MacBook Pro running OS Monterey and I've gotten the dreaded "Firefox is already open" message. Firefox isn't my primary browser but I do have tabs and bookmarks saved there. This has happened before, and last time I ended up following advice to delete my profile which wiped out my entire account (it was the only profile there, and I should have looked for an alternate solution because that clearly wasn't it).

I was very interested in switching from Chrome to Firefox permanently, but I'll be honest, I'm pretty frustrated that this keeps happening and putting my tabs/bookmarks/history/etc in jeopardy. If someone could provide a straightforward explanation as to how to fix this I would greatly appreciate it.

Btw, I already tried viewing FireFox in the activity monitor as I saw another site suggest and it wouldn't let me quit it (I saw it greyed out).

I use a MacBook Pro running OS Monterey and I've gotten the dreaded "Firefox is already open" message. Firefox isn't my primary browser but I do have tabs and bookmarks saved there. This has happened before, and last time I ended up following advice to delete my profile which wiped out my entire account (it was the only profile there, and I should have looked for an alternate solution because that clearly wasn't it). I was very interested in switching from Chrome to Firefox permanently, but I'll be honest, I'm pretty frustrated that this keeps happening and putting my tabs/bookmarks/history/etc in jeopardy. If someone could provide a straightforward explanation as to how to fix this I would greatly appreciate it. Btw, I already tried viewing FireFox in the activity monitor as I saw another site suggest and it wouldn't let me quit it (I saw it greyed out).

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There's a support article. You may have to remove a lock file although the lock file on my system (not Mac) does not seem to prevent me from starting Firefox.

https://support.mozilla.org/en-US/kb/Firefox-already-running-not-responding

有幫助嗎?

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Hello,

Thank you for responding! I don't think I saw that article when I was Googling solutions.

When I checked my Firefox profiles, I saw there were two (see attachment). I'm the only user on this computer. Does one of these need to be deleted? By the way, neither folder had a file with a .parentlock file.

有幫助嗎?

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Note that .parentlock is a hidden file on Mac.

有幫助嗎?

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Hello,

I was able to install follow another support article and install OnyX, which allowed me to locate and delete the hidden .parentlock files on my profiles. I was able to open FireFox again, but for some reason this completely wiped my FireFox account and made it a default profile again. I lost everything I had stored there. I was able to get the extensions I had back from the other profile by copying them over, but my bookmarks, history, tabs, etc are all gone (even though I copied all the files from the other profile over).

Very fortunately I didn't really lose anything important because FireFox is not my default browser, but I'm still pretty frustrated by this.

有幫助嗎?

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You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.


  • bookmarks and history: places.sqlite
  • favicons: favicons.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 (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
    key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
  • cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
  • persdict.dat for words added to the spell 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)

有幫助嗎?

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