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Firefox won't start after 6/21 update and causes crash in win 10

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Firefox won't start after 6/21 update and causes crash in win 10. Opening causes "Do you want to allow this app to make changes to your computer?" prompt. If I allow, FF does not open, Win slows and will crash. Trying to access/change Firefox profile or open FF in Safe mode does the same, so I cannot access these.

Firefox won't start after 6/21 update and causes crash in win 10. Opening causes "Do you want to allow this app to make changes to your computer?" prompt. If I allow, FF does not open, Win slows and will crash. Trying to access/change Firefox profile or open FF in Safe mode does the same, so I cannot access these.

การตอบกลับทั้งหมด (11)

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Hello kentmi, I noticed some other users recently with a similar problem which was caused by adware/malware. Here are a couple of tools which might help: Malwarebytes AdwCleaner and Norton Power Eraser

(Be sure to have Firefox closed when running scans)

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Thanks, but did not work. I ran the Malwarebytes tool and while it found some PUPS, it did not solve the problem. I tried opening FF with same result. I approved changes, and my computer slows to basic lock up. Win 10 task manager (via Ctrl Alt Del) will not function either once I give permission and I have to shut down with power button.

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Hi kentmi, Did you try Firefox in Safe Mode by press & hold the shift key while you launch?

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Yes, with the same result. Command prompt "firefox.exe -p" failed as well.

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You might want to consider backing up your profile and doing a clean install. Back up and restore information in Firefox profiles

Firefox keeps crashing at startup

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Thanks, My_Cheese_Is_Slippin, I appreciate your time and expertise. I've found my profile and copied to desktop. I understand my profile will not be deleted by a clean install and unless I delete it and this the problem can persist. Should I delete it and then restore it after a clean install?

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Hi kentmi. Don't delete the copy of your profile.

After you do a clean install, don't Restore your profile until you are convinced that Firefox is working properly.

If it is, then there is a problem in your profile. You can select files from your profile to restore like Bookmarks & Passwords, but I would re-check add-ons for possible malicious content.

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Got it. But should I delete my profile from C:\AppData\Roaming\Mozilla\Firefox\Profiles? Uninstall does not delete this. Thanks

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Hi kentmi, I would. There is also another part of your profile in C:\AppData\Local\Mozilla\Firefox\Profiles I would delete that one , also.

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Back up and running. I think good to go. Can I just copy and paste bookmarkbackups folder from old profile? Or just the last file in the folder? I did not copy C:\AppData\Local\Mozilla\Firefox\Profiles. Don't think this should matter.

Thanks so much for your patient assistance!

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Glad to hear it! Don't worry about the \Local\ folder. You should be able to copy the entire contents of the desktop folder to the C:\AppData\Roaming\Mozilla\Firefox\Profiles folder.