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.

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.

If you go into Safari --> Settings --> Privacy --> Advanced and uncheck "Privacy: Use advanced tracking and fingerprinting protection" you will be able to sign into your e-mail. You can then enable this feature again once you've successfully logged into your e-mail. There is no need to install chrome or change your default browser.

When your logging into gmail with Safari by default it launches a private browser to finish the transaction and having this feature enabled blocks whatever google is doing on the backend to validate your session.

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.

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.

I was having this issue after I changed my gmail password. I kept getting asked for my google login for internet accounts. I was able to resolve it by going into the privacy tab in safari settings and click on manage website data and removed all.

Chrome didn't work for me, but unchecking the Use advanced tracking and fingerprinting protection in the Safari Advanced settings as suggested by fw1engineer did the trick.

This will all depend on browser you have set as default on your iMac, Mac, or MacBook device. If its Safari, from the top task menu, make sure you see Safari listed, click on the Safari option, then click on the Privacy tab if you are on the latest version of MacOs Sonoma 14.2.1.

Then uncheck two boxes:

Website Tracking: Prevent cross-site tracking

Hide IP address: Hide IP address from trackers.

Go to the Contacts app and enter your credentials for Google. When you see all your contacts list, you can go back and enable the settings within Safari. I have not had any issues since two days ago.

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

Google is doing everything it can to FORCE people to use Chrome. In my situation, I could not access my Gmail account with Apple Mail. I was able to log into my account on the Gmail website. I think I tried just about everything suggested here. The "simple" fix was to make Chrome my default browser. Then all of the Google authentication gobley-goop went through just fine. After achieving this goal, I eagerly switched back to Firefox as my default browser.

We all know, Google would NEVER cause these problems intentionally.

@rostosha - This worked perfect for me! I had the issue for weeks. I did your steps to default to Chrome, then added my Gmail account and worked. Then just put the default back to Safari after it worked.

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.

"Changing the default browser to Chrome" is the indeed RESOLUTION!

Rbloomclu wrote:

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

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.

This issue only showed up after Google started pushing PassKeys and changed their security settings page. Something on their end messed this login process up.

Hopefully Apple and Google can figure it out and fix this issue as I think it will become a much bigger problem over time. On Apple's end - they should adjust any privacy settings blocking the ability to add the account in private browsing mode. On Google's end they should coordinate with Apple to make sure security changes work with various OS'.

I tried all the different privacy settings and content blocker features and was unable to get it working on Safari.

I used Chrome instead - set it to default, signed in and added the account, then switched back to Safari as the default -- as rostosha mentioned.

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.