Following VMWare KB 2146224 I was trying use the to reset the password Administrator@vSphere.local account so that I could sign in an make changes to the SSO identity providers.
When following the instructions and choosing option 3 I was getting a response
VmDirForceResetPassword failed (5)
I found that there is a known bug in vSphere and no fix, but just a work around. It was fairly simple, just logon to the server as the local administrator and run it again.