I got a case where a mailbox was not able to open Outlook. OWA and ActiveSync worked good. I also got information that the same mailbox had a working Outlook profile on another computer.
Tried all the known tricks of course (Repair profile, delete ost file, recreate profile. I even tried to delete mailbox and reconnect). The only thing that happened was this:
I opened RPC Client Access log on Exchange server under C:\Program Files\Microsoft\Exchange Server\V15\Logging\RPC Client Access .
I then compared a working user with the none working user: I then saw this ncacn_http is not allowed for this user, and also (StoreError=RpcHttpDisallowed).
I know that Exchange 2013 only uses RPC over HTTP, not MAPI as earlier.
Then I runned the command : get-casmailbox “user” | fl – And found this
Therefore I runned the command: set-CASMailbox “user” -MAPIBlockOutlookRpcHttp $false. And finally Outlook started.
And also the Outlook profiles that already set up was working (I guess this was did before MAPIBlocOutlookRPCHTTP was set to true), did not stop working. But only new outlook profiles was not working.