“Faceted Project Problem (Java Version Mismatch)” error message

Question

Eclipse\'s \"problems\" tab is displaying this error:

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

Answer 1

Did you check your Project Properties -> Project Facets panel? (From that post)

A WTP project is composed of multiple units of functionality (known as facets).

The Java facet version needs to always match the java compiler compliance level.
The best way to change java level is to use the Project Facets properties panel as that will update both places at the same time.

The "Project->Preferences->Project Facets" stores its configuration in this file, "org.eclipse.wst.common.project.facet.core.xml", under the ".settings" directory.

The content might look like this

Check also your Java compliance level: