That issue can be caused by corrupted cookies.

• https://support.mozilla.org/kb/Cannot+log+in+to+websites

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

See also:

• http://en.kioskea.net/faq/15289-google-nginx-404-error
• [/questions/811399]

Worked perfectly! Thanks, cor-el

Thank you very much cor-el. You just save me lots of time looking for the problem myself or deleting FF completely...

Under Tools, Firefox has no entry called "Options"...so this solution doesn't work...

Instead of Tools > Options use:

• Mac: Firefox > Preferences
• Linux: Edit > Preferences
• Windows: Firefox > Options

Press F10 if the menu bar is hidden on Windows and Linux or use "Firefox > Options/Preferences"

• https://support.mozilla.org/kb/Options+window