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.

Changing the default browser to Chrome resolved the issue. Then changed the default browser back to Safari.

In macOS Ventura or later

1. From the Apple menu  in the corner of your screen, choose System Settings.
2. Click Desktop & Dock in the sidebar.
3. Scroll down and choose a web browser from the “Default web browser” menu on the right.

In earlier versions of macOS

1. From the Apple menu  in the corner of your screen, choose System Preferences.
2. Click General.
3. Choose a web browser from the “Default web browser” menu.

In safari --> advanced - disable this while you set it up - that will resolve it.

I was able to fix this problem by going to Safari > Settings > Websites > Content Blockers and change “When visiting other websites” to “Off.” Also, clear all cookies/website data just to be safe.

At least in my issue, it seems that Safari was blocking Google’s authentication requests which led to the 400 error. When I changed that setting, it worked for me. Google uses multiple domains to authenticate (including google.com and youtube.com, and there may be others; I’m not sure). So it’s easier to just turn Safari’s content blocker off than try and find every possible domain Google uses to allow them all manually.

After successfully logging in, you can re-enable your content blocker again.

Same. Changing content blocker settings did not help. Can access gmail the Mail in my iPhone and iPad but not my MacBook.

I am having the same problem and the suggestion to change content blocker settings did not help.

If I try to submit a Question to the Public Forum for Google & Gmail I get this below; Can Anyone Please Tell Me Why I Am Not Even Allowed to Post a Question Anywhere Online About This?

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.

Thanks, your (@rostosha) suggestion worked for me, to temporarily switch to Chrome as default browser to let Google do its authentication thing. I suppose either Drew Powers' suggestion above to turn off content blockers, or EdZilla9's suggestion to keep using Safari but turn on cross-site tracking and turn off hide IP address from trackers, would have worked also.

Thanks. I also managed to resolve this by :

Changing the default browser to Chrome resolved the issue. Then changed the default browser back to Safari.

In macOS Ventura or later

1. From the Apple menu  in the corner of your screen, choose System Settings.
2. Click Desktop & Dock in the sidebar.
3. Scroll down and choose a web browser from the “Default web browser” menu on the right.

Thank you rostosha! changing the default browser to Chrome worked.

Changing the default browser to Chrome did the trick for me as well. Thanks!

For those encountering this issue…I contacted Apple Support where I was instructed to call Google Support’s line being 653-253-0000. I will advise you do not waste your time as that number does not work as I was suggested to call them since apparently it was a Google problem…thank you Apple Support for your mediocre suggestion.

The problem is not for you to contact Google Support. The issue lies on configuration settings inside the browser you are using. DrewPowers is correct on this detail.

If you are using Chrome as your primary browser in Mac computer, you may want to change your settings inside the browser to allow you to add your contacts if you delete or update your password (like I did) to avoid this issue.

Chrome configuration settings steps:

Open Chrome. There are two ways to access this detail.

1) By leaving the Chrome browser, click on the Apple task menu and select Chrome and then Settings.

On the browser address bar, you will see the following:

chrome://settings

Or on the top right side where the 3 downward buttons are, click on that and select Settings

2) Left hand side, you will see on the latest version of Chrome, Privacy and Security option. Click on that. In the middle of the page you will see a list of 6 options to select. Click on Third-party cookies.

3) From Third-party cookies menu, you will see 5 options. I am not 100% if I am correct but by default, “Block third-party cookies in Incognito mode” may be selected. Select “Allow third-party cookies”.

4) Click the back arrow and clear all your browsing data and then go back to the Contacts app and then enter your Google credentials to your account.

Follow the steps if you do not want to allow all third party cookies.

It should resolve your issue from there. Hope this works and thanks DrewPowers on the assist ^_^ Before I forget, I am on MacOs Sonoma 14.2.1

Go to google.com and download the Chrome browser, then install it.

Then in System Settings > Desktop & Dock > Default web browser, Chrome should be one of the items in the pop-up list. Set your choice to Chrome.

After you get your email password fixed, you can go back into System Settings and set Safari as your default browser again.

Thanks for your help. sadly, no change.

Something that has worked for me is to create an app specific password. Then create a new email iomap account using that password.

Create & use app passwords

1. Go to your Google Account.
2. Select Security.
3. Under "Signing in to Google," select 2-Step Verification.
4. At the bottom of the page, select App passwords.
5. Enter a name that helps you remember where you'll use the app password.
6. Select Generate.

This worked for me THANK YOU !