After entering start parameters for a remote debugging session on SQL Server 2005, a CoUnmarshalInterface failed with error code 0x80040155 error may display.
To resolve this issue:
1. Copy the ssdebugps.dll (SQL Server Debugging Host component) from the computer where SQL Server 2005 is installed to the same directory on the client computer. By default this directory is C:\Program Files\Common Files\Microsoft Shared\SQL Debugging.
2. Open a Command Prompt (i.e. Go to Start | Runand type cmd) on the client computer. Make sure you are in C:\Program Files\Common Files\Microsoft Shared\SQL Debugging at DOS prompt. Register the ssdebugps.dll by typing: regsvr32 ssdebugps.dll.
Note: If running a 32-bit SQL Server client, make sure you get 32-bit ssdebugps.dll and 64-bit with 64-bit ssdebugps.dll.
If connceting via VPN, TCP port 135 might need to be opened on the VPN firewall between the client and server for debugging to work.
