Unable to cast COM object of type 'System.__ComObject' to interface type for IRTDUpdateEvent

Question

I have spent a lot of time trying to figure out why I am getting the following error when trying to run RTD Server (Excel RTD Server) that I have developed when installing it via RegAsm. It works fine if I set the Register for COM interop flag on my dev machin, but not when install it using RegAsm.

System.InvalidCastException: Unable to cast COM object of type 'System.__ComObject' to interface type 'IRTDUpdateEvent'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{A43788C1-D91B-11D3-8F39-00C04F3651B8}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).

Any Ideas?

Answer 1

does your Interface "IRTDUpdateEvent" has this Guid?

Answer 2

Thanks Arthur,

I have at last managed to crack it. The problem was that when creating a setup package, I referenced the Assembley in my Custom Installation. It obviously did not like that when runing RTD. The RegAsm was in my custm installation. I solved the problem by leaving Register for COM interop flag checked and then adding the Assembley in my setup project by right clicking and sellecting Add --> Assembley.

Thanks