I was using the standard version from here:

https://addons.mozilla.org/en-US/firefox/addon/fvd-speed-dial/

I managed to fix it using the custom history settings located here:

https://everhelper.me/fix-57.php

I have the same problem trying to login to sync.  Chrome logs in and syncs fine.  Firefox 57 64-bit will not login.  "an error occured, please go back to login form"