{kb-symptom}
When trying to do an Exchange backup you receive the error below.
{code}
Unable to backup vss document
Protocol error, unrecognized message from agent
Could not start SQLWriter service: Unable to open sevice handle: The specified service does not exist as an installed service
September 05, 2012 5:22:30 PM CST - One or more devices failed replication
Error replicating device D:\ (E089F999844B6554)
Protocol error, expected block data stream
Error replicating device (AE003F44003F3DB5)
Protocol error, expected command response from agent
Error replicating device C:\ (8C6055326040F3D5)
Protocol error, expected command response from agent
{code}
{kb-cause}
This error is caused when the agent installed on the agent system is 4.0 as the Exchange protection was not released until 4.2.
{kb-resolution}
The resolution to this issue is to upgrade to 4.2.0 or higher.
{kb-related-articles}