Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Click the menu button , choose History, and then "Clear Recent History...".
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the "Clear Now" button.

Further information can be found in the Delete browsing, search and download history on Firefox article.

Did this fix your problems? Please report back to us!

I cleaned out the Cache and cookies and restarted. No luck. Same invalid request.

More options? Still no luck getting to gmail.

What do the error messages say?

If clearing cookies didn't help then it is possible that the cookies.sqlite file in the profile folder that stores the cookies got corrupted.

• Rename/remove cookies.sqlite (cookies.sqlite.old) and if present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder in case cookies.sqlite got corrupted.

You can use this button to go to the current Firefox profile folder:

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

• http://kb.mozillazine.org/Cookies
• https://support.mozilla.org/kb/Deleting+cookies