In Netbeans 6.9.1, i've created a web application wiht Glassfish Server 3.
(Undert the server textbox, java ee version defautls to "Java EE 6 Web").
Now I've installed an Apache tomcat 7 (actually it sees it as 6 because the 7 version was not provided in Netbeans 6.9.1).
The problem is that i'm no more allowed to choose Tomcat, it doesn't appear in the server combobox of the project properties.
If I do a web app from scratch, i can.
I tried to:
-remove WEB-INF/sun-config.xml
-close and reopen the project
If you created a Java EE 6 project, the IDE will not let you try to deploy it onto a server that does not support Java EE 6. NetBeans 6.9.1 does not distinguish between Tomcat 6 (which does Servlet 2.5) and Tomcat 7 (which supports Servlet 3.0). NetBeans 7.0 does know that Tomcat 7.0 can be used to deploy web apps that originally targeted GlassFish 3.0 or 3.1...
So the best solution for your situation is to install NetBeans 7.0.