Try one of these articles:
- Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work? Beginning in version 52, Firefox no longer loads NPAPI plugins except Adobe Flash. Find out how it works and what you can do about it.
- Refresh Firefox - reset add-ons and settings Restore Firefox to its default settings while saving essential data. This can fix slowness, crashing, search hijacking and other problems.
- How to troubleshoot the error code "SEC_ERROR_UNKNOWN_ISSUER" on secure websites This article explains why you might see the error code "SEC_ERROR_UNKNOWN_ISSUER" on HTTPS websites and how you can troubleshoot it.
- How to troubleshoot time related errors on secure websites This article explains why you might see time-related errors on HTTPS websites and how you can troubleshoot them by correcting your system clock.
- IMPORTANT ANNOUNCEMENT: We’re going through some system changes, that may have slowed responses to your questions. If you had asked a question in the last couple of months, please re-post it and the community will help you as soon as we can. If you’ve registered after February 7th, please register again, the accounts on the previous site were not migrated to this temporary site. If you joined us before February 7, please reset your password if you have trouble logging into this temporary site.