hello, do you get any particular error message? one thing you could try in any case is to clear the cache & cookies from google.com and reload the page.

I do not get an error message, only a refreshing of the sign-in page. I have cleared the cache and enabled cookies after reading every Google help suggestion.

Where do I find the cookie for Google?

this is explained at Clear cookies and site data in Firefox

in case clearing google's cookie didn't help, you can also try to refresh firefox and see if this can address the issue...

You can use the search bar in the Cookie Manager to search for Google cookies. "Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

You can inspect and manage the cookies for the domain in the currently selected tab:

• Click the "Site Identity Button" (globe/padlock) on the location/address bar
• Click "More Information" to open "Tools > Page Info" with the Security tab selected
• Click "View Cookies" to view the cookies for the domain in the currently selected tab

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page.

Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious and if you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of the involved files.

It doesn't have any lasting effect, so if you revisit such a 'forgotten' website then data from that website will be saved once again.