This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

Why wont Firefox start after latest update (Win 10)

  • 4 replies
  • 3 have this problem
  • 22 views
  • Last reply by B1keDude

B1keDude
B1keDude
more options

Firefox did one of its auto updates yesterday, and since then I cannot get it to start successfully. I see the process running in task manager, but it never displays. Have to manually kill the task to troubleshoot. Rebooted. Cleared all system cache, uninstalled Firefox, deleted all related folders, and re-installed. Nothing works. I hate IE, please save me from it.

Firefox did one of its auto updates yesterday, and since then I cannot get it to start successfully. I see the process running in task manager, but it never displays. Have to manually kill the task to troubleshoot. Rebooted. Cleared all system cache, uninstalled Firefox, deleted all related folders, and re-installed. Nothing works. I hate IE, please save me from it.

All Replies (4)

FredMcD
FredMcD
more options

There can be several reasons for this.

Firefox just released v58.

Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

  • Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
  • Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

B1keDude
B1keDude Question owner
more options

Thanks FredMcD. I went through all these steps, but I still cant get FF to open. I see the process running, but I never get a window. I have uninstalled several times, cleared system cache, followed your steps after a fresh install, nothing. The two things I noticed in following your steps are that 1st, I could remove all but one instance of Firefox from the list of trusted programs in Windows Firewall (this is a corporate machine, so I am sometimes limited as to what I can do), and 2nd, when I ran the Enum process, it showed Windows Firewall, and then listed Windows Defender as an element as well. I didn't find anything in Defender to change regarding trusted programs. Any other ideas or thoughts?

FredMcD
FredMcD
more options

About the firewall, contact your IT.


https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved You may have corrupt xulstore.json or Localstore.rdf file.

Close Firefox. Open your file browser to this hidden location:

  • Mac: *~/Library/Application Support/Firefox/Profiles
  • Linux: *~/.mozilla/firefox/Profiles
  • Windows: %AppData%\Mozilla\Firefox\Profiles
  • *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles
  • Windows XP: C:\Documents and Settings\<user>\Application Data
    \Mozilla\Firefox\Profiles\

Search for the above files. Then rename or delete them. Restart Firefox.

B1keDude
B1keDude Question owner
more options

Deleted 'Profiles' file. Restarted Firefox. No luck. Appreciate your efforts! Will talk to IT about possible firewall blocking. Ive been through tons of big Firefox updates over the years, and this is the first time this has happened :-(. If you think of anything else, please share, this is killing me. Cant get anything done. All my favorites are locked up in FF, and so are all my passwords. Thanks again.