There is 2 MS Exchange on-premise servers, 1 as CAS, and another as hub and MB servers. A hybrid coexistance with Exchange online is formed. However, I logon to the office365 portal, and attempt to migrate any mailbox from on-premise to online always ended with the error as attached.
I did an autodiscover test using MS remote testconnectivy, ended with pass. I also tested that the MRS Proxy server located on the CAS server is enabled. Any thing I missed out? please help to troubleshoot the issue.
Both exchange servers are running with 2010 sp3.
Thanks in advance.