Agent Errors 8524, 8604 and 2529 when Backing Up Exchange Server 2000 Remotely

Problem is backing up Microsoft Exchange Information Store (Exchange Server 2000) and Brick Level backup. ARCserve products in use are ARCserve 9 with SP1 and Patch 3.

Further environment details: ARCserve Manager is installed on Windows 2000 Advance Server with SP4, and ARCserve Exchange Agent is installed on Windows 2000 Advanced Server with SP4 and Exchange Server 2000 with SP3.

The backup of information store seems to be doing right. The job log would always contain this error message:
[tt]
E8524
Received unrecognized command from the client agent. (COMMAND=-69)
E8604
Failed to start backup. (DBNAME=First Storage Group, EC=)
[/tt]
At the end of the backup session however it would say that no errors occured.

It's hard to say if this has something to do with the size of the Information Store, but from my experience i know that another site i manage, it works although the error messages in the job log are the same, and the transaction files are deleted. In this case one Information Store was some 24GB and the other one was some 4GB, which leads to the conclusion this must have something to do with size. But then again, there are substantial differences between TCP/IP and Named Pipes in terms of security.

In addition to this, brick level would do ok one day, then the next day only back up a few mailboxes, lastly not backing up any mailboxes. The job log would look like this:
[tt]
[11/15/2003-17:02:24 ,0,0,0,0,0,2,1,0,0] \Individual Mailboxes\XXX
[11/15/2003-17:18:42 ,0,0,0,0,0,2,1,0,0] \Individual Mailboxes\YYY
[11/15/2003-17:18:45 ,0,0,0,0,0,2,1,0,0] E8604
[11/15/2003-17:18:45 ,0,0,0,0,0,2,1,0,0] Failed to start backup. (DBNAME=\Individual Mailboxes\ZZZ, EC=EXCH Exchange Agent -- (2529) \"Fail to Open Information Store\".)
[11/15/2003-17:18:45 ,0,0,0,0,0,2,1,0,0] \Individual Mailboxes\ZZZ
[11/15/2003-17:18:49 ,0,0,0,0,0,2,1,0,0] E8604
[11/15/2003-17:18:49 ,0,0,0,0,0,2,1,0,0] Failed to start backup. (DBNAME=\Individual Mailboxes\ZZZ1, EC=EXCH Exchange Agent -- (2529) \"Fail to Open Information Store\".)
[11/15/2003-17:18:49 ,0,0,0,0,0,2,1,0,0] \Individual Mailboxes\ZZZ1
[/tt]
The solution to Information Store Problem: When creating a backup job it is important that you select Named Pipes as remote protocol and that backup is done through Network Neighbourhood. Expand the computer, right click Microsoft Information Store you want to back up, select Remote Protocol and from the two possiblities select Named Pipes instead of TCP/IP.

The solution to Brick Level Problem: CA claims Exchange Server instability to be the reason why. There's a fix available which deals with this scenario. It's a Exchange Agent DLL-File (Dbaxchg2.dll) that needs to be replaced. The fix is numbered T367075.