If you install HIS 2009 or BizTalk Adapters for Host Systems 2.0 in order to use Transaction Integrator or the BizTalk Adapter for Host Applications, you might run into a scenario where the SnaBase service logs the following errors:
Event ID: 556Source: SNA Base ServiceDescription:A system error occurred while making a pipe connection, rc = 5
EXPLANATIONAn internal error occurred during an attempt to open a connection.
Event ID: 627Source: SNA Base ServiceDescription:Internal message routing error: process id 2588, mhtype 1, msgtype 19
EXPLANATIONThis is an internal error in Host Integration Server.
This can occur when you have defined a TI object as a WCF service similar to the example shown here and you are using LU 6.2 (APPC) sessions to communicate with the IBM host system.
Object Properties under Windows-Initiated Processing in TI Manager
Note: If you have defined the TI Remote Environment (RE) to use TCP/IP, this problem does not occur.
In this scenario, the SnaBase service will log the events listed above when an application calls the TI object.
The most straightforward way to resolve the issue is to go to the the Advanced Settings for the IIS Application Pool (e.g. DefaultAppPool) in IIS Manager and change the Identity from NETWORK SERVICE to ApplicationPoolIdentity. See here for an example showing the Identity set to ApplicationPoolIdentity.
Application Pool Advanced Settings in IIS Manager
The following article discusses the use of ApplicationPoolIdentity and how it will be the default in IIS 7.5:
Another option that worked for me was to change the Identity of the IIS Application Pool to the same user account that the SnaBase service was running under. However, this may not be the most ideal option as you may not want to have the application pool and the SnaBase service use the same credentials.