My ASP.Net-C# application works with mailmerge and the dll by name Microsoft.Office.Interop.Word.dll V14.0.0.0. All is well on my desktop (where office is installed). However when this application is deployed on the production machine, the following error is thrown:
System.Runtime.InteropServices.COMException (0x80040154): Retrieving the COM class factory for component with CLSID {000209FF-0000-0000-C000-000000000046} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)).
When the class is registered, the following error is found:
Microsoft.Office.Interop.Word.dll was loaded but the entry-point DLLRegisterServer was not found. Make sure, this is a valid dll or OCX and try again.
How do I fix this problem? Office suite can't be installed on the production machine.
No, the Interop libraries are just a shell over the real Office library code. Thus you need to have Office installed where your app is running
Also I totally agree with the comment above from John Saunders. You really should avoid to use these wrappers on a server application.
You can't, you can use OpenXML instead if you can't install Office at production server.
来源：https://stackoverflow.com/questions/19576080/can-microsoft-office-interop-word-dll-work-without-installing-office