dll reference Error in c# windows form App project - c#

I am trying to add a dll into my windows form application type project. However, when I am adding the dll to reference folder it is throwing an error and restricting me to add the same. Enclosed is a screenshot. Can anyone please let me know, under which condition we get this error and how to fix it?
Note: I am not aware, the dll has been produced using what tool or version/type of it.
screenshot of error
The message is:
A reference to C:\xyz.dll. dll could not be added, Please make sure
that the file is accessible and that it is a valid assembly or COM
component.

It's is exactly what you read and the message says.
Either thhis DLL doesn't contain any .NET code or class, or this DLL isn't a valid ActiveX DLL containing a typelib.
You can not add a DLL as a reference if it is not one of the above.
This is a possible duplicate to

Related

"Cannot get the file path for type library" trying to use OCX in .NET

I am rewriting an old VB6 application in c# on a Win10Pro64bit computer. The VB6 app uses an OCX called IMAGinE. I am able to add the control to the ToolBox. When I do, it adds two references: AxIMAGINELib and IMAGINELib. The IMAGINELib references has the little yellow triangle signifying there is an issue with the reference. I am able to add the control to the form. In the properties, it shows it is of type "AxIMAGINELib.AxIMAGinE". When I try to run the application, I get the following error in the "Error List" tab of VS:
Could not resolve COM reference "8a4feb20-a486-11cf-be99-0020afd208b9" version 1.0. Object reference not set to an instance of an object.
When I go to the Output tab of VS, it shows the following warning immediately preceding the above error:
Cannot get the file path for type library "bef6e001-a874-101a-8bba-00aa00300cab" version 2.0. Library not registered. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED))
A brief search seems to indicate that "bef6e001-a874-101a-8bba-00aa00300cab" points to olepro32.dll.
I have registered the OCX using regsvr32, both in the windows\system32 directory and windows\syswow64 directories. I registered olepro32.dll in the syswow64 directory, but not in the system32 directory because it didn't exist. Doing this did not change anything.
I removed the IMAGINELib reference and kept the AxIMAGINELib reference, thinking it wouldn't need both references and because the IMAGINELib reference had the little yellow triangle. Doing this did not change anything.
The company that created the original OCX is no longer in business, and I do not have the original component installer.
Any ideas what I can do to get this OCX working ? I don't want to use the OCX on a form. I need to access information that only the OCX can read. Thank you.

dll File not accessible

I know this question has been asked before but all the steps advised doesn't seem to work for me.
I am trying to use WebCamLib.dll to my project but it keeps giving me this error:
please make sure the file is accessible and that is a valid assembly
or com component
I tried to register the dll to SYSTEM32 and I get this error
The module C:\WebCamLib.dll" was loaded but the entry-point
DllRegisterServer was not found.
Make sure that "C:\WebCamLib.dll" is a valid DLL or OCX file and then
try again.
Please suggest a way. Thank you in advance.
The library you are trying to use is a managed library, you don't need to register it or use dllimport. Just add a reference from inside your project to the dll.
First option is DLL file may be corrupt. Make sure it is working with other applications.
My second opinion is you are trying to use this DLL as COM object which is not.

zlib.dll unable to add reference

I am working in VS 2012 C# and trying to add reference to zlib.dll, which I downloaded from ZLIB web-site. I am getting the following error message while trying to add reference:
A reference to 'C:\CTS\T4ClientSim\bin\zlib1.dll' could
not be added. Please make sure that file is accessible, and that is
a valid assembly or COM component.
I tried to launch VS as administrator, but it did not help.
Any help?

Reference 3rd-party C++ DLL into VS 2013 Project

I've been provided a DLL that has been written in C++. Along with the DLL I receive the required input parms and expected output as well as a .h include file.
Can't seem to get it included as a Reference in my project. My procedure is to right click References and Add Reference, click Browse and then double click on the DLL. The error I get is:
A reference to 'c:......\dll' could not be added. Please make sure
that the file is accessible, and that it is a valid assembly or COM
component.
The problem is likely due to the name mangling of C++, but I'm not sure how to overcome the problem. I've been told by the author of the DLL that it was written for another customer who ran into the same issue, but was eventually successful in getting it referenced. I don't have access to that 'customer' and was wondering if anyone had suggestions.
Adding a reference is not how you link to this unmanaged DLL from your C# code. Instead you need to either:
Translate the header file to C# p/invoke calls, or
Create a C++/CLI wrapper around the unmanaged DLL and add a reference to that from your C# project. This option would typically involve linking to the .lib import library for the DLL which should be supplied with the DLL.

Unable to open my C# project

I'm unable to open my project in Visual Studio 2008. It was developed in C# by my friend. It is showing the this error:
"Could not find type 'LibrarySystem.ctrlSeparator'.
Please make sure that the assembly that contains this type is referenced.
If this type is a part of your development project, make sure that
the project has been successfully built. "
Also
"The variable 'ctrlSeparator1' is either undeclared or was never assigned. "
How do I rectify this problem?
With all respect...the error message tells you everything you need to know...
It's trying to load a control, which does not exist. So either your friend didn't give you the whole project, or he used a Third-party-Component which you don't have.
Obviously your friend used (or wrote himself) a external library.
Ask him to provide you with this assembly, so that you can compile the project.
Either you don't have the complete project or you need to register dll. Make sure you have LibrarySystem.ctrlSeparator in code or assembly. If it is in unmanaged assembly then ask to friend whether it is needed to be registered.

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