This account already exists on your device - Fix / Solution - Android Pie 9.0

When I was setting up my replacement Google Pixel 3 XL I kept getting this error when setting up Google Home app and Google Pay app. I am sure other Google apps were affected but this is where I started to troubleshoot and research. 

Here is the error image:

GOOGLE ACCOUNT ERROR

I had a chat with Google Pixel support and they wanted me to remove my Google account and re-add it. I did not want to do this since I had just went through the trouble of copying / restoring my data on this phone. I suspect that was the problem to begin with. It was a brand new Pixel 3 XL to replace one that had a dead pixel. 

COPYING DATA

I saw a few reports of users disabling Google Play Services but Google has since removed the ability to disable the service. I suspect disabling the service caused it to "refresh" or "reset". So for me, the fix was to clear out the Storage of Google Play Services. Once I did that, and rebooted, everything started to work perfectly.  That is the fix for This account already exists on your device on Android Pie 9.0 Pixel 3 XL. 

Edit: For Android 11, it's changed a bit. Go to your phone settings, then click on Apps & Notifications, then click on See all apps. Look for Google Play Services. Click it, then click on Storage & Cache. Click Clear Storage and Clear Cache. 

CLEAR ALL DATA TO FIX