My experience
I used to encounter such problems until I understood the GAC and Bin deploy
All installed DLLs are installed on your computer in a place called GAC (Global Assembly Cache). therefore, your local programs can search for their needs there if they cannot find the necessary DLL in the execution path. It often works for the developer himself, but when you deploy your program to the client, problems can arise.
Remember that you can always use Bin to deploy your DLLs. first go to the link tree in your project and add the required Dll by looking at your GAC (usually c: \ windows \ assembly \ GAC_MSIL ...), then go to the properties window of the added Dll and set Copy Local to True . Now you can publish or deploy your project and make sure that it will work.
source share