Attach Debugger to IIS instance

In Visual Studio:

1. Click "Debug" from the menu bar
2. Click "Attach to Process"
3. Check the "Show processes from all users" checkbox in the bottom left corner
4. Select aspnet_wp.exe, w3p.exe, or w3wp.exe from the process list
5. Click "Attach"

The IIS process is aspnet_wp.exe.

In fact, attaching to the aspnet_wp.exe process is what VS does when you have your project set to use IIS for debugging.

The possible names of the ASP.NET process:

• w3wp.exe is IIS 6.0 and later.
• aspnet_wp.exe is earlier versions of IIS.
• iisexpress.exe is IISExpress.
• dotnet.exe is ASP.NET Core.
• inetinfo.exe is older ASP applications running in-process.

From Find the name of the ASP.NET process

You'll also need to open Internet Information Service From Control Panel > Administrative Tools. Right click the web site in question, click the home directory tab, and select the configuration button. This will open a new form with three tabs - click the debugging one and select the two options in the debugging flag section. This is also necessary to debug.

If you see the process [e.g. IIS Worker Process (w3wp.exe)] running is Task Manager, but not in the list of processes in debug > attach to process, you might need to run Visual Studio as administrator.