Ansible error - credssp: The server did not respond with pubKeyAuth info - ansible

Question

When running an Ansible script against a Windows server, I get the following error message.
credssp: The server did not respond with pubKeyAuth info auth was rejected
What is the cause of this.

Answer 1

I'm answering this question for myself because the solution was trivial to implement, but took some time to work out.
I was creating new EC2 instances with the following userdata which prepared the system as per the docs at http://docs.ansible.com/ansible/latest/intro_windows.html, and set the Administrator password.
<powershell>
Enable-WSManCredSSP -Role Server -Force
Set-Item -Path "WSMan:\localhost\Service\Auth\CredSSP" -Value $true
Invoke-Expression ((New-Object System.Net.Webclient).DownloadString('https://raw.githubusercontent.com/ansible/ansible/devel/examples/scripts/ConfigureRemotingForAnsible.ps1'))
$user=[adsi]"WinNT://localhost/Administrator,user"
$user.SetPassword("{{win_initial_password}}")
$user.SetInfo()
</powershell>
My Ansible script was waiting for a response on port 5986 (WinRM) before continuing, under the assumption that once this port responds the instance would be accessible.
What I believe was happening was that the Administrator password was not being set by the time port 5986 was responding.
To fix this I set the Administrator credentials as the first step in the userdata script, and added a pause for good measure.
<powershell>
$user=[adsi]"WinNT://localhost/Administrator,user"
$user.SetPassword("{{win_initial_password}}")
$user.SetInfo()
Enable-WSManCredSSP -Role Server -Force
Set-Item -Path "WSMan:\localhost\Service\Auth\CredSSP" -Value $true
Invoke-Expression ((New-Object System.Net.Webclient).DownloadString('https://raw.githubusercontent.com/ansible/ansible/devel/examples/scripts/ConfigureRemotingForAnsible.ps1'))
</powershell>
After these two changes, my script worked as expected. So if you get that error message, check the username and password are valid.