If you're encountering the 'could not copy obj debug netcoreapp2 to bin debug' error in your .NET Core project, you're not alone. This common build error can be frustrating, but there are a few potential solutions you can try to resolve it.

The error typically occurs when the build process is unable to copy the necessary files from the obj/debug/netcoreapp2 folder to the bin/debug folder. This can happen for a variety of reasons, including file locking, permission issues, or problems with the build configuration.

One potential solution is to manually clean and rebuild your project. This can help ensure that all necessary files are properly copied to the bin/debug folder. In Visual Studio, you can do this by right-clicking on your project in the Solution Explorer and selecting 'Clean' followed by 'Build'.

Another potential solution is to check for any file locking or permission issues that may be preventing the files from being copied. This can involve closing any programs that may be locking the files, ensuring that you have the necessary permissions to write to the bin/debug folder, and checking for any antivirus or security software that may be interfering with the build process.

If you're still encountering the error after attempting these solutions, it may be worth checking your build configuration for any potential issues. Make sure that your build settings are correctly configured and that there are no conflicts or errors that could be causing the problem.

In some cases, updating to the latest version of .NET Core or Visual Studio may also resolve the issue, as it could address any underlying bugs or compatibility issues that are causing the build error.

Ultimately, troubleshooting the 'could not copy obj debug netcoreapp2 to bin debug' error may involve a bit of trial and error, but by following these potential solutions, you should be able to get your project building smoothly again in no time.