Question

I have a .net assembly build in to sql. It works on all other sql servers, except on one system I get this error.

A .NET Framework error occurred during execution of user-defined routine or aggregate "GetCustomerData": 
System.IO.FileLoadException: The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
System.IO.FileLoadException: 
   at System.Diagnostics.TraceSource.Initialize()
   at System.Net.Logging.InitializeLogging()
   at System.Net.Logging.get_On()
   at System.Net.WebClient.DownloadString(Uri address)
   at System.Net.WebClient.DownloadString(String address)
   at CustFromPhone.BaseFunctionClass.GetCustInfo(SqlString PhoneNo)

Answer 1

You simply have wrong manifest data for your .NET binaries

An assembly manifest contains all the metadata needed to specify the
assembly’s version requirements and security identity, and all
metadata needed to define the scope of the assembly and resolve
references to resources and classes.
http://en.wikipedia.org/wiki/Manifest_%28.NET_Framework%29

This is why its corrected when you rebuild it.