Mozilla VPN is currently experiencing an outage. Our team is actively working to resolve the issue. Please check the status page for real-time updates. Thank you for your patience.

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.

Problems with installation of Thunderbird and Firefox in Windows 10

  • 1 reply
  • 1 has this problem
  • 5 views
  • Last reply by FredMcD

alevizos
alevizos
more options

When i installed Thunderbird and Firefox at my laptop in Windows 10 they don't run and i receive the following messages: "Thunderbird (Firefox) is already running, but is not responding. The old Thunderbird (Firefox) process must be closed to open a new window."

When i installed Thunderbird and Firefox at my laptop in Windows 10 they don't run and i receive the following messages: "Thunderbird (Firefox) is already running, but is not responding. The old Thunderbird (Firefox) process must be closed to open a new window."
Attached screenshots

All Replies (1)

FredMcD
FredMcD
more options

Reboot the computer and try again.


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

https://www.basezap.com/cant-open-firefox-because-a-copy-of-firefox-is-already-open-mac/

https://apple.stackexchange.com/questions/196771/cant-open-firefox-because-a-copy-of-firefox-is-already-open

http://kb.mozillazine.org/Firefox.exe_always_open