What if the file exists and the path is correct, but I still get a 404 error on localhost IIS?

In this case, consider these less common causes: Check if the 'Directory Browsing' feature is disabled and you're trying to access a directory without a default document (like index.html). If you are using ASP.NET, ensure the correct version is installed and configured within IIS, and that ASP.NET is properly mapped to handle requests. Also, verify that the file isn't being blocked by any security settings or antivirus software. Finally, try restarting the IIS service itself (using `iisreset` in the command prompt) to clear any cached data or configuration issues.