Java compiler level does not match the version of the installed Java project facet

Question

I have created a New Dynamic Project under Eclipse Helios Version, where my JRE Version is set to 1.6. I have added Maven capabilities to the Web Application by clicking on

Answer 1

I changed the configuration inside workspace/project/.setting/org.eclipse.wst.common.project.facet.core to :

installed facet="jst.web" version="2.5"
installed facet="jst.java" version="1.7"

Before changing config, remove project from IDE. This worked for me.