I get a 400 error every time I attempt to add Gmail account

This was happening with me (an existing Gmail account inaccessible via Mail), and when I called Apple Support, they indicated there is an issue with Safari and Google. They had me install Chrome, make that my default, and then when I re-accessed Mail, it took the password and verification code and allowed me to use Gmail again. Maybe that will help with your issue.

I was getting an error in Apple Calendar after resetting my Google password, and got the error 400 when trying to reconnect the Google account in Safari. Changing the default to Google Chrome allowed me to reconnect the account, although I had deleted the Google account from MacOS. Everything seems to be working now after switching the default browser back to Safari.

Lakshmime9 you are a rock star. I fought this issue for days and setting Chrome as my default browser worked like a champ. Many thanks for sharing.

lucas159 wrote:

Me too. I am trying to add my gmail account to apple mail and getting the same error.

Have tried solutions in other posts but nothing has worked for me. I removed the account due to a password reset and tried adding it back in and cannot get it back in apple mail.

Google support couldn't help you with their mail account?

Read BDAqua response here Can’t login to Gmail from old iMac - Apple Community

Midnight1LE wrote:

I have 2 email accounts on my MacBook Pro's mail app and every time I try to add my 3rd account for my business I receive an error message from Google reading "400. That’s an error.

The server cannot process the request because it is malformed. It should not be retried. That’s all we know."

Is anyone else experiencing this issue and if so how could I fix it?

Thank you in advance for anyone with any information on this.

[Re-Titled by Moderator]

https://support.google.com/mail/?hl=en

Me too. I am trying to add my gmail account to apple mail and getting the same error.

Have tried solutions in other posts but nothing has worked for me. I removed the account due to a password reset and tried adding it back in and cannot get it back in apple mail.

Thank you, your suggestion of changing to Chrome worked! I was a bit worried because I deleted the "offline" account and was afraid it would not come back at all. Whew!

It worked! Thanks. Now to see what happens when I make Safari the default browser again.