Could not create content describer for com.example.cstfile. Content type has been disabled

Question

I'm trying to add a content type for my XML files with a custom file extension(CST) and I get the following error - Could not create content describer for com.example.cstfile. Content type has been disabled.

Here's my plugin.xml file -

<extension point="org.eclipse.core.contenttype.contentTypes">
      <content-type
            base-type="org.eclipse.core.runtime.xml"
            file-extensions="cst,xml"
            id="cstfile"
            name="CST File"
            priority="normal">
         <describer class="org.eclipse.core.runtime.content.XMLRootElementContentDescriber2"
                    plugin="org.eclipse.core.runtime">
            <parameter name="elementNames" value="CSTFile"/>
         </describer>
      </content-type>
      <file-association 
            content-type="org.eclipse.core.runtime.xml"
            file-extensions="cst">
      </file-association>
</extension>

I'm trying to figure out the reason by debugging org.eclipse.core.internal.content.ContentTypeCatalog but have not found any reasons so far, any help is appreciated.

Answer 1

It looks like it comes from calls to ContentTypes.invalidateDescriber - the content describer has thrown an exception.

Looking at XMLRootElementContentDescriber2 it will throw an exception if it gets a javax.xml.parsers.ParserConfigurationException exception when try to parse the XML.

There should be more information in the .log file in the .metadata directory of the workspace.