Can't connect Gmail to Macmail (Sonoma 14.2.1 on M3 MacBook Pro)

The issue appears to be Safari's "advanced tracking and fingerprinting protection". Go to Safari's Settings -> Advanced and uncheck "Use advanced tracking and fingerprinting protection".

After this I was able to re-authenticate my Google account without the 400 Bad Request error. Once the account is reconnected, you can enable the option again.

Help! I have the same issue, since Dec 2013. But, the solution that appears to have worked for everyone in the above posts, has one problem...There is no, "Settings -Advanced," on my MAC, or on my Safari browser. Where do I go to find the elusive box to uncheck, "Used advanced tracking and fingerprinting protection?"

bosmacs, this solution enabled me to add two different gmail accounts to two different Apple computers that previously gave the 400 error. Thanks a lot for posting this! How did you ever figure this out?

Doesn’t work for me !

I had this problem too, a 400 error code after I changed my Google password, kept me from using Apple Mail on a Macbook. But this solution worked immediately! Thank you!

This worked for me.

I had the same issue. I have multiple gmail accounts but one of them stopped syncing with my apple mail on my iMac and MacBook. Was OK on my IOS devices. Spoke with Apple support and was fixed in a few minutes. This is their fix.

Hi *********, further to our call please see the following information that could be of help to you. Safari Settings>Privacy and uncheck ‘Prevent cross-site tracking and Hide IP address from tracker. System Settings>Desktop and Dock and set the default browser to Google Chrome. Put Safari settings back and made safari the default browser again.

I am experiencing this too. Are you by chance also trying to log in to a "non-gmail" branded account (e.g. business or education)?

Worked for me!

WOW ! ! Thank you, THANK YOU!! This worked ! !

jabartram, Sorry, I meant to say that I've had this problem since Dec. 2023. Also, you are correct. This MAC desktop is a late 2012 model, and Apple stopped offering an OS upgrade since High Sierra v10.13. Maybe, because of this, there is no solution apart from a major hardware upgrade!

I have an Intel MAC book pro running Ventura 13.6.4.

Same problem I updated by google password and could not log into gmail, no such problem on IOS. Got the 400 error, device retired. This worked for me

1) I changed my default browser to chrome.

2) Went to "Internet Accounts" under system settings

3) Select add account "Google"

4) Validate on Google App on iPhone for two step validation

Google seems to see Safari as an unsupported device for account validation.

This worked, and is ridiculous. Try to keep account secure and change password and you are faced with this problem.

Change back to safari after as default browser after you fixed this