The operation couldn’t be completed. Unable to log in with account 'myappleid'. An unexpected failure occurred while logging in (Underlying error code 1100).

While still in Xcode, I simply went to Signin + Capabilities and simply clicked Sign In under the Apple ID.. that solved it.

In my case, Xcode Preferences -> Account Tab -> Sing In again

So this happened to me. To resolve it, I had to go to Xcode > Preferences > General tab. It then told me my session expired and to reenter my password for my account. Try that

Go to Property> Signing and Capabilities > you have to enter your Apple ID password.

if you can change register apple account password. then this issue is created.

now you can add register email and change password and restart your Xcode. and see work will be fine.

i hope this information help you.

thank you..