Are you encountering the error message 'Could Not Copy obj Debug netcoreapp2 to bin Debug' when working on your .NET Core application? Don't worry, we've got you covered with some troubleshooting tips to help you resolve this issue.

1. Clean and Rebuild: Start by cleaning your solution and then rebuilding it. Sometimes, this simple step can resolve the issue by removing any corrupted or outdated build artifacts.

2. Check File Permissions: Ensure that you have the necessary permissions to copy the obj Debug directory to the bin Debug directory. Sometimes, file permission issues can cause this error message to appear.

3. Check for Locked Files: Another common cause of this error is locked files within the obj or bin directories. Use a file system tool to check for any locked files and release the locks if necessary.

4. Close Visual Studio: In some cases, Visual Studio may hold onto files within the obj Debug directory, preventing them from being copied to the bin Debug directory. Try closing and reopening Visual Studio to release any locks.

5. Update Visual Studio: Ensure that you are using the latest version of Visual Studio and .NET Core SDK. Updating to the latest releases can fix any known issues related to the build process.

6. Check for Build Errors: Look for any build errors in the Output window of Visual Studio. Addressing any build errors can help resolve the underlying cause of the copy error.

7. Exclude Files: If you have any files within the obj Debug directory that are causing the copy error, consider excluding them from the build process. This can be done through the project properties in Visual Studio.

By following these troubleshooting tips, you can effectively address the 'Could Not Copy obj Debug netcoreapp2 to bin Debug' error and get back to developing your .NET Core application with confidence. If you continue to experience issues, consider reaching out to the .NET Core community or Microsoft support for further assistance.