How can I troubleshoot/diagnose Firefox browser issues?

Support issues sometimes indicate, or lead to the consideration of, browser issues. Follow the link below to troubleshoot and diagnose issues with Mozilla's Firefox browser.

The article at the link below provides Mozilla's recommended set of steps to follow if Firefox is no longer working properly. It offers solutions that will preserve user profile data (bookmarks, passwords, history, preference settings, etc.) as far as possible.

The article also provides links to Mozilla's knowledge base and links to common problems.