Auth 2.0 Error 400 on Mail account

I try to add my account but I got this message


Authorisation Error
Error 400: invalid_request

You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy for keeping apps secure.

You can let the app developer know that this app doesn't comply with one or more Google validation rules.
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redirect_uri: urn:ietf:wg:oauth:2.0:oob



What's wrong with Apple and Google? Google asks to contact the developer, yes Apple...


It's so frustrating...

Posted on Feb 22, 2023 2:58 AM

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Question marked as Best answer

All advice given here does not solve the problem unfortunately. What is the solution?

Posted on Feb 23, 2023 6:36 PM

184 replies

Jun 4, 2023 11:06 PM in response to ays177

  • Generate app specific password on google
  • System Preferences -> Internet Accounts -> Add CalDAV account
  • Set account type to Advanced
  • Set user name to google account (yourusername@gmail.com)
  • Set password to app specific password previously generated
  • Set server address to: https://calendar.google.com
  • Set server path to: /calendar/dav/yourusername@gmail.com/user/
  • Set port to: 443
  • Put a checkmark in: Use SSL
  • Leave "Use Kerberos" unchecked


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Jun 6, 2023 10:22 AM in response to ays177

Thank you for the post but ...


Wait for it-- drumroll.............


Of course we all saw this coming--


In Google Security there isn't an 'Apps' tab to select-


There is a "Recent Security" section listing your device activities with dates


"How to Sign in to Google" with a list of things like-


2-Step Verification

Password

Google Prompt

2-Step Verification Phones

Recovery Phone

Recovery Email


"Your Devices"


"Third Party Apps with account access"


"Enhanced Safe Browsing For Your Account"


"Signing In to Other Sites"


"Looking For Something Else?"


So which is it?

Jun 18, 2023 1:28 PM in response to ays177

I spoke too soon about it working for me. About 10 minutes after I reconnected after deleting the old gmail account and adding it back through the 'other' option, I got this warning from my mac as a pop up message (i'm assuming after checking for mail via push notifications):


MAIL CANNOT ACCESS YOUR MAILBOX INFORMATION BECAUSE IT'S ALREADY IN USE


Another application on your computer or your local network is using your mailbox information. Click QUIT to quit mail. Then log out of this compute rand any other computer you're using. After you log in again, open Mail on one computer only.


If this message reappears, there may be a network server problem. Contact your system administratro to determine if it can be resolved by rebuilding your mailbox information. Then click Rebuild Mailbox Information.


******

Since my computer is so old there are thousands upon thousands of emails with attachments....rebuilding would take days at the least.

Anyone else get this and how did they handle it?

I'm using the same gmail account on my iphone and also another Mac but I assumed the generated Gmail password would only apply to and affect THIS computer running High Sierra.


Any thoughts? Does this mean I can only have my email running on one computer a time now?

Auth 2.0 Error 400 on Mail account

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