Error : The Web application at [URL] could not be found.

Hi,

I am trying to run a simple code like finding all the users in the SharePoint site.

But I am seeing this error constantly no matter what I do!!

The Web application at [URL] could not be found. Verify that you have typed the URL correctly. If the URL should be serving existing content, the system administrator may need to add a new request URL mapping to the intended application.

I’ve changed project properties ‘Any cpu’ to x64 and tried but failed.

Thanks