|Component:||Microsoft Exchange Recipient Update Service|
|Message:||Unable to open LDAP session on directory ‘<directory name>‘ using port number <value>.Directory returned the LDAP error:[0x<error code>] <error message>. <connection agreement name>|
This event indicates that the Recipient Update Service (RUS) was unable to contact a domain controller. The directory may not be available, or the name of the domain controller specified in the properties of the Recipient Update Service may be incorrect.
Check the status of the directory and verify that the domain controller name is correct in the Recipient Update Service. Verify that the specified domain controller is up and running and is reachable from the Exchange server. Occasionally this issue may occur if the Kerberos ticket for the server has expired. If this is the case, the problem corrects itself on the next attempt.