java.lang.NoClassDefFoundError: org/eclipse/xtext/service/AbstractGenericModule

Question

after more than a day of searching i am really stuck in resolving the problem of a eclipse xtext RCP.

launching the .product results in the error:

java.lang.NoClassDefFoundError: org/eclipse/xtext/service/AbstractGenericModule

the result is, that non of the DSL-Editors show up. instead a blank Tab is created in the RCP. except a comprehensive stack trace, the eclipse IDE is not very precise in it's expression of the problem.

so far i am using:

• eclipse Neon (201606...)
• Xtext 2.11
• Maven 3.5.x

Product configuration:

<?xml version="1.0" encoding="UTF-8"?>
<?pde version="3.5"?>

<product name="XXXXXXXXXX" uid="com.xxxx.xxxx.xxxxx.product" id="com.xxxx.xxxx.xxxxx.product.product" application="org.eclipse.ui.ide.workbench" version="1.0.0.qualifier" useFeatures="false" includeLaunchers="true">

   <configIni use="default">
   </configIni>

   <launcherArgs>
      <programArgs>-consoleLog
      </programArgs>
      <vmArgs>-Dfile.encoding=UTF-8
      </vmArgs>
      <vmArgsMac>-XstartOnFirstThread -Dorg.eclipse.swt.internal.carbon.smallFonts
      </vmArgsMac>
   </launcherArgs>

   <windowImages/>

   <launcher name="mss-testbench">
      <solaris/>
      <win useIco="false">
         <bmp/>
      </win>
   </launcher>

   <vm>
      <windows include="true">org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8</windows>
   </vm>


<plugins>
      <plugin id="ch.qos.logback.classic"/>
      <plugin id="ch.qos.logback.core"/>
...


<configurations>
      <plugin id="org.eclipse.core.runtime" autoStart="true" startLevel="4" />
      <plugin id="org.eclipse.equinox.common" autoStart="true" startLevel="2" />
      <plugin id="org.eclipse.equinox.ds" autoStart="true" startLevel="2" />
      <plugin id="org.eclipse.equinox.event" autoStart="true" startLevel="2" />
      <plugin id="org.eclipse.equinox.simpleconfigurator" autoStart="true" startLevel="1" />
      <plugin id="org.eclipse.osgi" autoStart="true" startLevel="-1" />
      <plugin id="org.eclipse.update.configurator" autoStart="true" startLevel="3" />
      <property name="org.eclipse.update.reconcile" value="false" />
   </configurations>

   <preferencesInfo>
      <targetfile overwrite="false"/>
   </preferencesInfo>

   <cssInfo>
   </cssInfo>

</product>

please let me know if you need more details. many thanks