This error is hard to explain, but it is one of thoughs errors that work on Version 3 of the Navision Application Server and not in version 4. If there is an nassql.exe fix for this I would be really happy to get my hands on it. The error explained: I develop third party applications and services using .Net. My applications communicate to Navision via the MSMQ (Microsoft Message Queing) which is the read by the Navision Application Server, to process invoices etc, which altimately brings Navision business logic to my .Net assemblies. If an error occurs in the Navision coding e.g. " Error(‘My Error Message’); " The Navision Application Server automatically sends a message to the MSMQ server by means of it’s build in bus adapter. in Version 3 of Navision this error xml that the Nav Application Server send can be converted into a .Net class. In Version 4 of the Nav Application Server this error xml produced is currupt. – If anyone has had the same problem. Please let me know if you have a resolution or a critical update that i may have missed?