Unable to create editor ID org.eclipse.emf.ecore.presentation.EcoreEditorID: org.apache.xerces.jaxp.SAXParserFactoryImpl cannot be cast to javax.xml.parsers.SAXParserFactory
java.lang.ClassCastException: org.apache.xerces.jaxp.SAXParserFactoryImpl cannot be cast to javax.xml.parsers.SAXParserFactory at javax.xml.parsers.SAXParserFactory.newInstance(Unknown Source) at org.eclipse.emf.ecore.plugin.EcorePlugin.computePlatformPluginToPlatformResourceMap(EcorePlugin.java:302) at org.eclipse.emf.ecore.plugin.EcorePlugin.computePlatformURIMap(EcorePlugin.java:424) ...
It looks like this occurs when two plugins register two different SaxParserFactorys.
In my case, it seems it was that I had both the Ecore and ATL plugins installed at the same time; removing the ATL plugin resolved this error.