I have 5 Gmail accounts that I have been using in Thunderbird for years. One of them was glitching a lot, so I removed it, then tried to add it back with no luck. I uninstalled and reinstalled Thunderbird, which automatically populated with my other four accounts, but still can't reinstall the fifth account. When I enter my account and password, it says "Configuration found in Mozilla ISP database" with a green checkmark. Then it takes me to Google, and shows my correct email address. When I hit Next, I get a 400 error message every time. "The server cannot process the error because it is malformed. It should not be retried. That's all we know." Can anyone help?