RPC_S_SERVER_UNAVAILABLE (0x6BA) error code when you use a MAPI or CDO-based application in an Exchange Server 2010 environment

Applies to: Exchange Server 2010 Service Pack 3Exchange Server 2010 EnterpriseExchange Server 2010 Standard


Consider the following scenario:
  • You use a MAPI or Collaborative Data Objects (CDO)-based application to log on to a mailbox in a Microsoft Exchange Server 2010 environment.
  • Your user account is the last logon object on the remote procedure call (RPC) connection.
  • The application does not send a remote operation (ROP) request for more than 2 minutes.
  • The application tries to log you off from the mailbox.
In this scenario, the Microsoft Exchange RPC Client Access service throws a ServerUnavailableException exception. Additionally, the RPC_S_SERVER_UNAVAILABLE (0x6BA) error code is returned in the application.


To resolve this issue, install the following update rollup:
2803727 Description of Update Rollup 1 for Exchange Server 2010 Service Pack 3


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.