A reference to the dll could not be added

user_20358 0
Viewed 227500

When I add a .dll file as a reference in C# application it shows an error :

A reference to the "....dll" could not be added.Please make sure that the file is accessible and that it is a valid assembly or COM component.

ILDissassembler says there is no valid CLR header so I try to register it using regsvr32 and that gives me another error:

The module "" was loaded but the call to DLLRegisterServer failed with error code '0x80004005'

I am using VS2010 ultimate version on a 64bit Windows 7 machine. What could be the problem?

Thanks for any hints/replies

wcf reference .net
18 Answers

I had this issue after my PC has been restarted during building the solution. My two references gone, so I had to rebuild my two projects manually and then I could add references without error.

user_25492580

I needed to change architecture to x86 from x64 in configuration manager and copy my 32 bit dll (C language - pcProxAPI.dll) into new folder this created.. This is on top of the steps described by "Sashus" below.

C:\Projects..\bin\x86\Debug

user_32544050

I had the same problem when I tried to add a dll I just coded in C++ to my new C# project. Turned out I needed to set properties of the C++ project my dll is from:

  • Configuration Properties\General\Common Language Runtime Support: /clr
  • Configuration Properties\C/C++\General\Common Language RunTime Support: /clr

Because the C# project in which I wanted to use this dll was also set like that (had the same properties set to /clr).

user_83772870

You can add .dll file manually. For example if you want to add a dll file in your WPF application, and you are unable to refer it in your project

(Getting error :A reference to the "....dll" could not be added.Please make sure that the file is accessible and that it is a valid assembly or COM component) ,

then COPY that dll file and PASTE in the INSTALLER PROJECT (in application folder).

user_130602550
  1. start cmd.exe and type:
  2. Regsvr32 %dllpath%
  3. "%dllpath%" replace to your dll path
user_81121530

I had the same problem when I tried to add my own c++ dll to a c# (4.7.2) project

c++ project was compiled as x86 (win32) c# was complied as x86

the solution was to compile the c++ as CLR

user_173275700
Related