Class not registered Error

The problem is that the DLL is registered on the 32 bit version of the windows registry, and the application is using the 64 bit version.

Solution: Go into the Project Properties, Compile tab and click "Advanced Compile Options...". Change "Target CPU" to x86, click OK, save and try again.

Source: http://www.theogray.com/blog/2009/10/comexception-regdbeclassnotreg-on-64-bit-windows

Has worked for me with an VB 6 COM DLL invoked from a .Net 4 Winforms application

Somewhere in the code you are using, there is a call to the Win32 API, CoCreateInstance, to dynamically load a DLL and instantiate an object from it.

The mapping between the component ID and the DLL that is capable of instantiating that object is usually found in HEKY_CLASSES_ROOT\CLSID in the registry. To discuss this further would be to explain a lot about COM in Windows. But the error indicates that the COM guid is not present in the registry.

I don't much about what the PackAndGo DLL is (an Autodesk component), but I suspect you simply need to "install" that component or the software package it came with through the designated installer to have that DLL and appropriate COM registry keys on your computer you are trying to run your code on. (i.e. go run setup.exe for this product).

In other words, I think you need to install "Pack and Go" on this computer instead of just copying the DLL to the target machine.

Also, make sure you decide to build your code appropriate as 32-bit vs. 64-bit depending on the which build flavor (32 or 64 bit) of Pack And Go you install.

In 64 bit windows machines the COM components need to register itself in HKEY_CLASSES_ROOT\CLSID (64 bit component) OR HKEY_CLASSES_ROOT\Wow6432Node\CLSID (32 bit component) . If your application is a 32 bit application running on 64-bit machine the COM library would typically look for the GUID under Wow64 node and if your application is a 64 bit application, the COM library would try to load from HKEY_CLASSES_ROOT\CLSID. Make sure you are targeting the correct platform and ensure you have installed the correct version of library(32/64 bit).

Long solved I'm sure but this might help some other poor soul.

This error can ocurre if the DLL you are deploying in the install package is not the same as the DLL you are referencing (these will have different IDs)

Sounds obvious but can easily happen if you make a small change to the dll and have previously installed the app on your own machine which reregisters the dll.

I had the same problem. I tried lot of ways but at last solution was simple. Solution: Open IIS, In Application Pools, right click on the .net framework that is being used. Go to settings and change 'Enable 32-Bit Applications' to 'True'.

I had run into the same problem. I added reference of Microsoft.Office.Interop.Excel COM component's dll but Office was not installed on my system it wont give compile time error. I moved my application to another system and ran it..it worked successfully.

So, I can say in my case it was the system environment which was causing this issue.

I had this problem and I solved it when I understood that it was looking for the Windows Registry specified in the brackets.

Since the error was happening only in one computer, what I had to do was export the registry from the computer that it was working and install it on the computer that was missing it.

I was getting the below error in my 32 bit application.

Error: Retrieving the COM class factory for component with CLSID {4911BB26-11EE-4182-B66C-64DF2FA6502D} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)).

And on setting the "Enable32bitApplications" to true in defaultapplicationpool in IIS worked for me.

For me, I had to install Microsoft Access Database Engine 2010 Redistributable and restart my computer.