Learn about the error codes SEC_ERROR_UNKNOWN_ISSUER MOZILLA_PKIX_ERROR_MITM_DETECTED and ERROR_SELF_SIGNED_CERT on HTTPS websites and how to troubleshoot.
Learn why you might see time-related errors on HTTPS websites and how you can troubleshoot these errors by correcting your system clock.
This page explains the error: "Website will not allow Firefox to display the page if another site has embedded it"
A Refresh can fix many issues by restoring Firefox to its default state while saving essential information like bookmarks and passwords.
Firefox certificate pinning reports; what they are and why you might want to share yours.
How to report a broken website and what information Mozilla receives when you report breakage caused by Enhanced Tracking Protection.
The Troubleshooting Information page has tools and details about your Firefox installation, that can help you solve problems with Firefox.
Learn how to reset your Firefox "user agent" so that websites can detect your correct browser and version and work the way they should.
When accessing a site with SSLv3, Firefox will block it and display an "Unable to connect securely" message.
You may be selected to rate Firefox or complete a survey. You may also see a notice to update Firefox. Learn more about these messages.
Accessibility features are not yet fully supported in multiprocess Firefox. Restart Firefox to change it back to single process mode.
Some Windows accessibility tools might turn off Firefox's multi-process support. Here's how to re-enable it.
There is a known issue with WindowBlinds and hardware acceleration that causes crashing in Firefox. Here are some workarounds you can try.
The API hooks from Citrix XenApp 7.13 VDA do not work with 64-bit Firefox. How to find a workaround.
Firefox's "about:performance" page shows you what tabs or add-ons are making Firefox slow.
Learn how to add an exception for Pocket in Firefox, to prevent being prompted to log in to Pocket when saving to the site.
How to disable the Enterprise Roots preference to fix TLS connection errors caused by antivirus software, without compromising security.
How to resolve an issue where Firefox asks for a Primary (formerly "Master") Password if you have AVG or Eset Internet Security installed.
If each open Firefox tab shows up in your Windows volume mixer, a fix will be released in Firefox version 76. Here is a workaround in the meantime.
There was a known issue in Firefox version 69 and Beta 70 that prevented you from downloading files in Windows 10 when parental controls were on.
Firefox Compatibility with Windows Exploit protection.
[https://send.firefox.com/ Firefox Send] has been discontinued as of September 17th, 2020. Thank you for trying Firefox Send in the past.
Learn about workaround for a CCleaner but that's deleting saved Firefox extension settings in Firefox 79.
AppCache is being disabled starting with Firefox 80. Here's how to re-enable it (advanced only).
How to work around a known issue with Twitter on Firefox.
How to fix the NS_ERROR_DOM_ABORT_ERR while trying to open web.telegram.org or app.slack.com on Firefox 87 or above.
Firefox searches going to the wrong website can be caused by your Internet provider, an add-on, toolbar or malware. Learn how to fix this.
Learn how to troubleshoot and fix Firefox crashes, and find out how to get more help if you're having problems solving the issue.
Learn why Firefox may start in Troubleshoot Mode (previously known as "Safe Mode") when you expect it to start normally and how to fix it.
Firefox may repeatedly open empty tabs or windows after you click on a link, forcing you to close Firefox. Learn how to fix this problem.
You can reset your Firefox primary (formerly "master") password if you forgot it. Warning: This removes all saved usernames and passwords.
Learn how to troubleshoot and fix printing problems in Firefox.
If Firefox has trouble playing video or music on a Windows computer, you can install the Media Feature Pack, if it's missing. Learn more.
Here are some easy things you can do to avoid crashes and keep Firefox running in tip-top shape.
This article links to solutions for the latest Firefox issues like problems with Flash not loading or crashing.
Find out the right direction to get help using webmail in Firefox and links to support pages for popular web-based email services.
If Firefox keeps crashing when you try to start it and other solutions don't work, a clean reinstall can often fix the problem.
Learn how to restore your home page if a third-party software vendor changes it so that their page always opens when you launch Firefox.
Set up Firefox to open multiple home pages replacing the pipe character (|) with %7C.
This article shows you what to do if you cannot add new bookmarks or make other changes to your bookmarks.
How to fix the error ''Your Firefox profile cannot be loaded. It may be missing or inaccessible'' so that you can start and run Firefox.