Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

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

unable to connect to firefox

  • 1 reply
  • 3 have this problem
  • 1 view
  • Last reply by cor-el

more options

I click on Firefox icon & get an error of "This application has failed to start because plc4.dll was not found". I don't want to really re-install as I want to keep my bookmarks. Is there anyway around this?

I click on Firefox icon & get an error of "This application has failed to start because plc4.dll was not found". I don't want to really re-install as I want to keep my bookmarks. Is there anyway around this?

All Replies (1)

more options

Do a clean (re)install and delete the Firefox program folder (C:\Program Files\Mozilla Firefox\).

Download a fresh Firefox copy and save the file to the desktop.

Uninstall your current Firefox version, if possible.

  • Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you will also lose your personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

Your bookmarks and other profile data are stored elsewhere in the Firefox Profile Folder and won't be affected by a reinstall, but make sure that you do not select to remove personal data if you uninstall Firefox.