When I log on as Administrator to either .../ecp or .../owa, authenticaion, I believe, succeeds but then I get HTTP 500.
When I do this on another server hosting the Exchange server for the same Organisation, I succeed - can get into both the mailbox and the Exchange server ECP interface. Unlike the first server, this Exchange server does not host any mailboxes but otherwise has identical Exchange roles installed.
When I log on as another non-administrator user to the first server that hosts mailboxes, I again succeed.
The problem seems to relate the administrative interface that the first server somehow fails to display but what could be the reason for that?
Thank you.