I have debug Java Desktop Applications various times in Netbeans but haven\'t debug Java Web Application ever.
I tried to debug it the same way, but it\'s not working.
Also sometimes, I don't know why the project detaches itself from the debugger process, you just need to select the menu Debug -> Attach Debugger and attach the project again. For example in Glassfish just put localhost as the server and 9009 as the port and it will work again
How did you start your web application in debug mode? On my machine, I simply select the project, click on the Debug top menu, then Debug Project, select a Server (GlassFish, WebLogic, Tomcat) if required and things just work (I can place a breakpoint in a Servlet and the execution stops there). Tested with all the mentioned containers.