I tried to open an application of mine on 64bit OS having Window 7 and IIS 7.5 and I ran into this problem. This is due to following issue.
- IIS running on a 64Bit Operating System
- The Assembly DLL in question has been compiled for 32Bit – check the project properties under the build tab, if under platform target you have x86 then it is 32bit only.
The issue is that the 64Bit IIS machine is using an Application Pool that is not allowing a 32bit DLL to be processed.
- Just Check you project configuration
- Goto IIS Manager — > Application Pools — > Advance setting of the pool your application is using