An existing connection was forcibly closed by the remote host - WCF

Question

I have a WCF web service that is working fine. However there is one particular call that is failing - but only failing for certain users. The call is pretty simple - it is

Answer 1

After pulling my hair out for like 6 hours of this completely useless error, my problem ended up being that my data transfer objects were too complex. Start with uber simple properties like public long Id { get; set;} that's it... nothing fancy.