Question: I'm new to from xamarin and I'm trying to publish my app xamarin ios, So when I [try to uploading it to the app store,](https://i.stack.imgur.com/1hDIX.png)
I got the following error.

Answer: 
The error is obvious. It said *Authentication Failed*.

You should sign in with an app-specific password. Create the password at <https://appleid.apple.com>.
@Raptor's answer above worked for me with the following specifics:

I had to change my Apple account password. After changing my Apple account password, my app-specific password was gone from my Apple account. I needed to create a new app-specific password. The complete list of steps I needed to restore my ability to publish apps with Visual Studio (after changing my Apple account password) is as follows:

1. Open XCode > Preferences and re-sign into my account (XCode showed that my account login had expired). I signed in with my new password.
2. Open Visual Studio > Preferences > Apple Developer Accounts and remove and re-add the account (login with new password)
3. Visit <https://appleid.apple.com> and within the Security block, click the "Edit" button to confirm that your app-specific password is gone. Then click "Generate Password" and use the new app-specific password when publishing apps.