Sorry, no default certificates to download. Fastest way (7mins) to fix this to uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 59.0.1 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

Hi cryptic_saiyajin, how did you delete all your certificates? Was it through the Certificate Manager or did you remove a cert8.db or cert9.db file?

What error code are you getting? On the error page, click the "Advanced" button if there is one. The code usually has ALL_CAPS. This article discussed the most common one, which is Firefox not being set up to work with your security software:

How to troubleshoot security error codes on secure websites

If you mean that you removed builtin root certificate then you can delete cert9.db and cert8.db to restore all builtin certificate. You can't actually remove these certificates, but they are merely hidden in the Certificate Manager.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox