"error 400: invalid_request" in MacMail using my Gmail account

This answer is almost useless, since many computer's cannot be upgraded to the current macOS that support the security requirements for Gmail. You probably need macOS Mojave or newer (with updated Mail).

Unfortunately you will need to use Safari or other browser to log into Gmail directly on older machines.

Date: 21 Mar 23

I was getting the same EM as the OP but in the iMac Calendar (Version 10.0 (2195.4.3)) I'm running OSX 10.13.6 on a late 2009 iMac. Google calendars would not update. calendar events created on Android phones and iPad would not sync to the iMac and events created on the iMac would synch back to other devices.

Reading the above and comments elsewhere made be think that I would need to upgrade the iMac which is beginning to creak a bit.....BUT by selecting the google calendar, then going to Calendar Info and unchecking the Enable this account box, closing the Calendar app, reopening and re-enabling the account the EM disappeared and everything is now syncing across devices and loading normally.

Hope this might help somebody.

Try Thunderbird app for mac. It's similar to Mac Mail, but allows High Sierra OS. I just figured this out. So far so good.

www dot thunderbird dot net download

[Edited by Moderator]

Hello supriya133,

To help resolve any potential compatibility issues we recommend ensuring your devices are up-to-date. Here's how: Update macOS on Mac - Apple Support

Should you continue to experience an issue with this specific email account we recommend reaching out to Google directly. You can review support options here: Gmail Help

Take care.

Hey guys - found this - it worked

https://code2care.org/macos/fix-mail-authorization-error-400-invalid-request/

I have the same issue and it's frustrating since I will not upgrade my Mac above High Sierra. Apple has totally messed up their OS after HS.

I have several accounts that are gmail accounts I use. This is the worst thing that could happen but it's not just happening on High Sierra, it's also happening on my iPhone and iPad that are up to date.

So I hope someone comes up with a solution or I might as well buy a PC.

I have replied to you before. You cannot pass the buck to Google. Why does my one Gmail account work and the other will not recognise the "username or password?".

There is an internal error with Mac OS who should resolve it. Mac OS you messed up.

I have wasted hours trying to fix but was able to use my phone, but some things need an actual computer. I am old and used to the software and will not rush out and get a new computer. I will have to use an alternative non Apple software programme and adjust to that as it seems others are having to do.

I am very disappointed with Apple/Mac.

Nothing new found. I have had to work around it. My Mac is dying a slow death! That is what Apple have done and planned! You cannot find alternative email apps as they will not work on the software as it stands or ridiculous costs involved and then of course insecure servers in various parts of the world that I would not trust. I can only use Mail for iCloud emails. My other Gmails are via Firefox!

“Happy Mac-ing”

I have being having the same problem on my iMac but after many days wasting time I have finally fixed the problem.

I hope this is helpful here is the link that helped

https://code2care.org/macos/fix-mail-authorization-error-400-invalid-request

Authorisation Error

Error 400: Invalid_request has not allowed me access to my Gmail both receiving and sending.

Thank you Jules_70. The this link had a vital piece of information regarding setting up "another account" in Mail, not trying to set up a "Google" account.

I have exactly the same problem suddenly my MAIL that has been working for years has kicked out my main email account. This is AWFUL!

Apple do something about it. I have spent hours trying all the tricks!

I have done a full OS reinstall. I am on High Sierra 10.13.6 (17G14042)

This is an Apple problem not Google. My one account works but the other has now died on me! I have reinstalled the OS. I am using High Sierra 10.13.6

Error 400

Thank you. That worked!