If you are connecting to a remote instance.
Ensure the msvsmon.exe the remote debugging service is running.
Ensure the ports are accessible through firewall.
Ensure your user has access to remote debug. This can be set in the remote debugging tool.
Ensure the solution is built and deployed in debug mode
Ensure the Visual studio version is same or less than ...
I looked how Sitecore timers for debug mode are implemented, and modify my code:
public class SomeTypeModelBinder : IModelBinder
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
Tracer.Info("Starting BindModel for SomeType");