We're calling on all EU-based Mozillians with iOS or iPadOS devices to help us monitor Apple’s new browser choice screens. Join the effort to hold Big Tech to account!

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.

will not boot up

  • 1 reply
  • 1 has this problem
  • 12 views
  • Last reply by cor-el

tom_baltezor
tom_baltezor
more options

When trying to open firefox the following message appears.

Firefox is already running, but not responding. The old Firefox process must be closed to open a new window. If I pic Close Firefox the error message goes away but comes back. I've tried uninstalling and reinstalling with and without resetting to default but no help. Same issue appears.

When trying to open firefox the following message appears. Firefox is already running, but not responding. The old Firefox process must be closed to open a new window. If I pic Close Firefox the error message goes away but comes back. I've tried uninstalling and reinstalling with and without resetting to default but no help. Same issue appears.
Attached screenshots

All Replies (1)

cor-el
cor-el
  • Moderator
  • Top 10 Contributor
more options

Try to delete parent.lock in the profile folder.

Location used for the main profile that keeps your personal data.

  • C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>

You can create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.