When updating a Maven project you can come accross the error Unsupported IClasspathEntry kind=4. This is due to a bug in m2e, which can manifest itself when using the m2e plugin on a project that has generated Eclipse project settings via the Maven maven-eclipse-plugin

Solving Unsupported IClasspathEntry kind=4

1. Install the latest version of the m2e plugin – which adds Maven functionality into Eclipse.
2. Disable the maven nature of the project (right-click on the project)
3. Run mvn eclipse:clean (right click on the project -> Run As -> Maven build .. -> Goals: eclipse:clean)
4. Re-enable the maven nature by right-clicking on the project and choosing Configure-> Convert to Maven Project
5. Don’t run maven-eclipse-plugin