Unable to loging to Exchange 2013 OWA or ECP : You don't have permission to open this page. If you're a new user or were recently assigned credentials, please wait 15 minutes and try again.

Issue :-  Unable to login to ECP or OWA with newly install Exchange 2013 or Exchange 2013 sp1. 

Error :-

You don't have permission to open this page. If you're a new user or were recently assigned credentials, please wait 15 minutes and try again. 

or 

Something Went wrong :(

Please check  Application logs stating same.

Windows logs -> Application logs

(Process w3wp.exe, PID 6460) "RBAC authorization returns Access Denied for user CAS\Administrator (SID=S-1-5-21-2801702198-531129156-3484030250-500). Reason: User was not found on Domain Controller dc.domain.com."

Resolution :-

We all have normal habit of putting administrator word as account name in login is the issue.  please use administrator@domain.com you will be able to login.

I believe Microsoft should fix this soon. why a local Account request is going to CAS server.

Regards,

Ajay Chanana