Solving error S0433 “Type ‘X’ already exists in both A.dll and B.dll

When managing projects, you might encounter issues after making changes that result in a new build. These problems often arise when Visual Studio fails to replace all the contents in your application’s obj or bin folders. Consequently, some files in your application’s bin folder may become outdated.

Here’s a step-by-step guide to resolving this issue:

1. Close Visual Studio: Ensure that Visual Studio is not running.
2. Perform an IIS Reset: This will refresh your IIS server.
3. Delete Temporary Files: Go to the “Temporary ASP.NET Files” folder and delete all folders and files. The path to this folder should be noted in the error message.
4. Remove Obj and Bin Folders: Delete the “obj” and “bin” folders from your application’s directory.
5. Restart Visual Studio: Open Visual Studio again and load your solution.
6. Clean and Rebuild the Solution: Perform a “Clean Solution” followed by a “Rebuild Solution” to ensure all changes are properly applied.