HTTP 404 while getting https://mail.server.kz/owa/login.aspx

Hello,

I have made new Exchange 2013 SP1 installation with CAS frontend server and mailbox backend server.

I have played with OWA and ECP authentication. I have broken it and have recovered again but now I have a problem with authentication to owa and ecp. When users enter their login/password they redirect to https://mail.server.kz/owa/login.aspx and after it they redirect to https://mail.server.kz/owa/auth/errorFE.aspx?httpCode=404:

https://mail.server.kz/owa/auth/logon.aspx?replaceCurrent=1&url=https%3a%2f%2fmail.server.kz%2fowa%2flogin.aspx

If user enters https://mail.server.kz/owa/ he gets correct page and then everything works fine.