# Web App Classpath Problem

You were directed to this help topic because your server code needed a class or resource that was not found on the web app classpath, but was found on the system classpath. The system classpath is the classpath you specify when launching the Java VM to run hosted mode. The web app classpath is different — it consists of classes that live in your web application's war directory. All server classes and dependencies should to be placed in your war directory: libraries (jars) should be placed in `war/WEB-INF/lib/` and classes that don't live in jars should be placed in `war/WEB-INF/classes/`.

GWT hosted mode helpfully works around this problem by mapping these outside resources into your web app classpath. This warning reminds you that failing to address the issue can lead to problems when you actually deploy your web app to a real server.

## Tips

- The most common reason to encounter this problem with a new project is using RPC, which tries to load `com.google.gwt.user.client.rpc.RemoteService`. The solution to is copy `gwt-servlet.jar` from the GWT install directory into your web app's `war/WEB-INF/lib/` directory.
- If you have a good reason for not following the recommended configuration, you can suppress warning by setting the Java system property `gwt.nowarn.webapp.classpath`. Specify `-Dgwt.nowarn.webapp.classpath` as a JVM argument when launching hosted mode.