Failed to authenticate with Google...?

Hi. I had the same issue. I've fixed it by deleting Google Drive File Stream, which was not functioning on my mac because of I haven't G Suite account. I guess if you haven't completely setup any app related to Google, you will have that kind of issues.
Hope this will help.
Cheers!

Same here.

I've tried all of the relevant "solutions" others have used. None have worked. And I received this error on two MacBook Pros. On one, the error stopped, but I have no idea why. On the other, the error has persisted to the point that I've given up.

I have experienced this issue lately. And keeps telling authentication failed even when the password is absolutely correct (tired logging in in Gmail.com). How did you solve this?

I was having the same issue with the authentication failed message continually popping up. Deleting and re-adding the account did not work. The fix that finally worked for me was using my ATT phone as a hotspot. Xfinity is my ISP and for whatever reason the authentication would not work as long as I was using home network.

I had the same problem. Try sending an email (using Apple Mail) from each of the email accounts synced with Apple Mail. If this is successful, then this post will not help.

If not, you'll see options corresponding to the smtp server lists. This is where my previous settings said "smtp.gmail.com". Instead select "www.google.com" or "www.gmail.com". Now, you should be able to send emails. Once this goes through, my iCal synced properly almost simultaneously.

Hope this helps.

Best,

This was the only thing that helped me, I've been working to fix this problem for months. I was clicking "google mail" as the account type .. i went to add different type of account and typed it in myself. It finally worked!! Thank you

It's keeping ask to authenticate and failing!!

Try looking here.

Google Support

Google Support is useless. It just shows you how to change your password, but that is not the problem. You don't get to the "authentication failed" stage if you haven't entered your password correctly. It's something deeper than that. Most "fixes" posted on the Net are for Android devices, but this isn't a problem on my iPad or iPhone - only on my desktop iMac, and only since the last couple of updates of Yosemite.

If your computers clock is not set to the correct date and time you will get this.

Check your Date and Time.

How is that relevant to the Google issue?

I have the same problem- a notification appears saying 'Google Password required', so i follow the steps -continue -to a page titled Internet accounts, listing iCloud, and two google accounts. I have a separate gmail account, and a .mac, .me, .cloud account that are all aliases of my original mac.com account. It asks me to sign in to my gmail account, accepts my password, spins for bit, a mysterious page with some code appears for a milisecond, and then the 'authentication failed' appears. I am able to access my mail, and the internet, but the notification is annoying at best and worrisome. I too recently upgraded to OS X....

I had this when it was working before.

I checked the gmail address and it was different to my current address - so I just deleted the Google calendar entry and re-created it with the correct email address and it solved my problem. It was originally configured with googlemail.com and was working - now everything is converted to gmail.com the issue popped up during conversion I am guessing.

I'd be interested to know if this fixes anybody else.

The thing is I don't use Google calendar or gmail. Of course I have a gmail address, but it seems to have the same password as all my other Google things. It's not a password issue, because it is very quick to reject a mistyped password - it's the next stage, the "accepting" stage where it all breaks down. I love this latest OS upgrade because start-up and opening most apps is so much quicker, but under the previous OS version it was only iCal that demanded a password, so I only got a notification when I looked at my calendar, but now it's for all Google things. I still wouldn't like to guess whether it's the OS or Google's bringing everything together that is causing the problem.