Occasional error on production server: Method <name> is not supported on this proxy

Question

One of 4 production servers once in a while generates tons of error claiming:

Method RunRules is not supported on this proxy, this can happen if the method is not marked with OperationContractAttribute or if the interface type is not marked with ServiceContractAttribute.

The method "RunRules" is one of the methods in wcf [ServiceContract] interface, and it is marked as [OperationContract].

Before this error, in the same method, occasionally it would get a wrong service through castle container. After I put more logging information to nail down exact cause, it mutated into the current error.

It is a webservice the error comes out of, it tries to call into a windows service through wcf endpoint when this happens. And this only happens on one specific machine. The frequency is about once a week or 2 weeks. Once recycle of the webservice happens (3 hours), the error stops.

To me it is almost like corrupted vtable. Just wondering, how would you approach this problem? Hate to ask IT people start to re-image the machine without solid proof.

Thanks!

Answer 1

No simple answer for such abstract magic error, so try out logging entire call stack, especially internal Castle DLL calls, if standart exception does not contain such deep call stack information - use reflection.

// use this in loop incrementing levelIndex up to st.FrameCount
// to grab all possible callstack entries
StackTrace st = new StackTrace();
st.GetFrame(levelIndex).GetMethod().Name;

Then using utility like ILSpy disassemble Castle DLL and try out analyze which state causes concrete execution flow which ends up with exception you got.

If you able log callstack - please share so I would be able check it as well.