"Updating Maven Project". Unsupported IClasspathEntry kind=4

This occure if you are upgrading to maven 3.

Make sure that the version of the m2e(clipse) plugin that you're running is at least 1.1.0. The update site is here: https://repository.sonatype.org/content/repositories/forge-sites/m2e/1.1.0/N/LATEST/

and run:

mvn eclipse:clean