How to Fix the 'Class Not Registered' Exception in COM Applications?

Resolving "Unregistered Class" exception in COM applications

While creating an instance of a COM class, an error occurred: "Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG))". This exception indicates that the target COM class is not properly registered on the system.

Troubleshooting:

To resolve this issue, please follow these steps:

1. Reinstall the COM component: Uninstall and reinstall the COM component associated with the class you are trying to instantiate. This will ensure that the necessary registry keys are registered correctly.

2. Make sure the assembly has the correct architecture: Verify that all assemblies referenced by the application are compiled for the same architecture. If you are targeting a 32-bit application, all assemblies must be compiled for 32-bit. If you are targeting a 64-bit application, all assemblies must be compiled for 64-bit.

3. Manually register COM classes: If reinstalling the COM components does not resolve the issue, you can use the regsvr32 utility to manually register the COM classes. Open a command prompt as administrator and run the following command:

   <code>regsvr32 <COM文件路径></code>

   Replace <COM文件路径> with the full path to the COM file (.dll or .ocx) you are trying to register.

4. Update registry permissions: Make sure the registry key for the COM class has the appropriate permissions. Navigate to the following registry key:

   <code>HKEY_CLASSES_ROOT\<ProgID></code>

   where <ProgID> is the programmatic identifier (ProgID) of the COM class. Grant your account the necessary permissions to read, write, and create subkeys in this registry key.

By following these steps, you can resolve the "Class Not Registered" exception in your COM application and successfully create an instance of the COM class.

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