Hello, I have been using Drools 5.3.0.FINAL until now. I am upgrading my running system with 5.4.0.FINAL. The bundles are all runing. I got some error messages and tried to reduce the problem and created a simple bundle. The code only inserts facts and after 20 facts I get the following error: [ERROR] [System] - Exception in thread "Thread-8" java.lang.ExceptionInInitializerError [ERROR] [System] - at org.drools.concurrent.ExecutorProviderFactory.getExecutorProvider(ExecutorProviderFactory.java:12) [ERROR] [System] - at org.drools.rule.constraint.MvelConstraint$ExecutorHolder.<clinit>(MvelConstraint.java:208) [ERROR] [System] - at org.drools.rule.constraint.MvelConstraint.jitEvaluator(MvelConstraint.java:199) [ERROR] [System] - at org.drools.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:164) [ERROR] [System] - at org.drools.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:124) [ERROR] [System] - at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:137) [ERROR] [System] - at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:59) [ERROR] [System] - at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:235) [ERROR] [System] - at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:240) [ERROR] [System] - at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:337) [ERROR] [System] - at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:298) [ERROR] [System] - at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:123) [ERROR] [System] - at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:53) [ERROR] [System] - at de.pelle7.drools.test1.simpletest.SimpleTestDrools$1.run(SimpleTestDrools.java:74) [ERROR] [System] - Caused by: java.lang.IllegalArgumentException: Unable to instantiate service for Class 'org.drools.concurrent.ExecutorProvider' [ERROR] [System] - at org.drools.util.ServiceRegistryImpl.get(ServiceRegistryImpl.java:162) [ERROR] [System] - at org.drools.concurrent.ExecutorProviderFactory$ExecutorProviderHolder.<clinit>(ExecutorProviderFactory.java:8) [ERROR] [System] - ... 14 more [ERROR] [System] - Caused by: java.lang.IllegalArgumentException: Unable to instantiate 'org.drools.concurrent.ExecutorProviderImpl' [ERROR] [System] - at org.drools.util.ServiceRegistryImpl$ReflectionInstantiator.newInstance(ServiceRegistryImpl.java:213) [ERROR] [System] - at org.drools.util.ServiceRegistryImpl$ReflectionInstantiator.call(ServiceRegistryImpl.java:205) [ERROR] [System] - at org.drools.util.ServiceRegistryImpl.get(ServiceRegistryImpl.java:160) [ERROR] [System] - ... 15 more [ERROR] [System] - Caused by: java.lang.ClassNotFoundException: org.drools.concurrent.ExecutorProviderImpl [ERROR] [System] - at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:506) [ERROR] [System] - at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:422) [ERROR] [System] - at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:410) [ERROR] [System] - at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107) [ERROR] [System] - at java.lang.ClassLoader.loadClass(Unknown Source) [ERROR] [System] - at java.lang.Class.forName0(Native Method) [ERROR] [System] - at java.lang.Class.forName(Unknown Source) [ERROR] [System] - at org.drools.util.ServiceRegistryImpl$ReflectionInstantiator.newInstance(ServiceRegistryImpl.java:210) [ERROR] [System] - ... 17 more The Rule file: package de.pelle7.drools.test1.users.rules.impl; import de.pelle7.drools.test1.simpletest.*; import org.jbpm.ruleflow.instance.*; rule "Funny Rule #1" dialect "java" when $testObject : TestObjectA( value == 0 ) from entry-point "my_entry" then System.err.println("New Item: " + $testObject); retract($testObject); end If I change the line --> $testObject : TestObjectA( value == 0 ) from entry-point "my_entry" to --> $testObject : TestObjectA( ) from entry-point "my_entry" there is no problem. In the java code i initialize a Drools Session programatically and add one rule file: package de.pelle7.drools.test1.simpletest; import java.io.InputStream; import java.net.URI; import java.net.URL; import java.util.Collection; import java.util.HashSet; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import org.drools.KnowledgeBase; import org.drools.KnowledgeBaseConfiguration; import org.drools.KnowledgeBaseFactoryService; import org.drools.builder.KnowledgeBuilder; import org.drools.builder.KnowledgeBuilderConfiguration; import org.drools.builder.KnowledgeBuilderFactoryService; import org.drools.builder.ResourceType; import org.drools.definition.KnowledgePackage; import org.drools.io.ResourceFactory; import org.drools.io.ResourceFactoryService; import org.drools.runtime.StatefulKnowledgeSession; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class SimpleTestDrools { public static final String DEFAULT_ENTRY = "my_entry"; private static Logger logger = LoggerFactory.getLogger(SimpleTestDrools.class); private StatefulKnowledgeSession droolsSession; private KnowledgeBuilderFactoryService droolsKnowledgeBuilderFactoryService; private ResourceFactoryService droolsResourceFactoryService; private KnowledgeBaseFactoryService droolsKnowledgeBaseFactoryService; public static Logger getLogger() { return logger; } public StatefulKnowledgeSession getDroolsSession() { return droolsSession; } public void start() { KnowledgeBuilder kbuilder = getDroolsKnowledgeBuilderFactoryService().newKnowledgeBuilder(); KnowledgeBaseConfiguration config = getDroolsKnowledgeBaseFactoryService().newKnowledgeBaseConfiguration(); //config.setOption( MBeansOption.ENABLED ); KnowledgeBase knowledgeBase = getDroolsKnowledgeBaseFactoryService().newKnowledgeBase(config); droolsSession = knowledgeBase.newStatefulKnowledgeSession(); LinkedList<URI> resourcesList = new LinkedList<URI>(); try { resourcesList.add( getClass().getResource("MyDrools.drl").toURI() ); addResources(droolsSession, getDroolsKnowledgeBuilderFactoryService(), resourcesList); } catch (Exception e) { e.printStackTrace(); } new Thread() { public void run() { try { Thread.sleep(5000); } catch (InterruptedException e) { } System.out.println("Go 1"); for (int i = 0; i< 1000; i++) { System.out.println(i); getDroolsSession().getWorkingMemoryEntryPoint(DEFAULT_ENTRY).insert(new TestObjectA()); getDroolsSession().fireAllRules(); try { Thread.sleep(1); } catch (InterruptedException e) { } } System.out.println("Go 2"); }; }.start(); System.err.println("wait"); //getDroolsSession().fireUntilHalt(); } public static void addResources( StatefulKnowledgeSession droolsSession, KnowledgeBuilderFactoryService droolsKnowledgeBuilderFactoryService, List<URI> resources ) throws MyDroolsException { getLogger().debug("Drools: Register: " + resources); MyDroolsException exception = null; KnowledgeBuilderConfiguration lnowledgeBuilderConfiguration = droolsKnowledgeBuilderFactoryService.newKnowledgeBuilderConfiguration(); HashSet<URI> defects = new HashSet<URI>(); KnowledgeBuilder kbuilder = null; while (true) { URI uriError = null; kbuilder = droolsKnowledgeBuilderFactoryService.newKnowledgeBuilder(lnowledgeBuilderConfiguration); try { Iterator<URI> it = resources.iterator(); while (it.hasNext()) { URI uri = (URI) it.next(); if (defects.contains(uri)) { continue; } StringBuilder builder = new StringBuilder(); builder.append("Adding drools file '" + uri.toString() + "'"); URL url = uri.toURL(); InputStream iStream = url.openStream(); ResourceType resourceType; String path = uri.getPath().toLowerCase(); resourceType = ResourceType.determineResourceType(path); getLogger().debug(builder.toString()); kbuilder.add(ResourceFactory.newInputStreamResource(iStream), resourceType); // Check the builder for errors if (kbuilder.hasErrors()) { uriError = uri; //getLogger().error(kbuilder.getErrors().toString()); String errorMessage = kbuilder.getErrors().toString(); kbuilder.getErrors().clear(); throw new MyDroolsException(errorMessage); } try { iStream.close(); } catch (Exception e) { e.printStackTrace(); } } } catch (Throwable e) { if (uriError != null) { defects.add(uriError); } String msg = "Error in Resource '" + uriError + "'"; getLogger().error(msg); e.printStackTrace(); if (exception != null) { exception = new MyDroolsException(msg, exception); } else { exception = new MyDroolsException(msg); } exception = new MyDroolsException(e.getMessage(), exception); continue; } // All done! break; } final Collection<KnowledgePackage> pkgs = kbuilder.getKnowledgePackages(); droolsSession.getKnowledgeBase().addKnowledgePackages(pkgs); if (exception != null) { throw new MyDroolsException("Error while adding resources!", exception); } } public KnowledgeBuilderFactoryService getDroolsKnowledgeBuilderFactoryService() { return droolsKnowledgeBuilderFactoryService; } public void setDroolsKnowledgeBuilderFactoryService( KnowledgeBuilderFactoryService droolsKnowledgeBuilderFactoryService) { this.droolsKnowledgeBuilderFactoryService = droolsKnowledgeBuilderFactoryService; } public ResourceFactoryService getDroolsResourceFactoryService() { return droolsResourceFactoryService; } public void setDroolsResourceFactoryService( ResourceFactoryService droolsResourceFactoryService) { this.droolsResourceFactoryService = droolsResourceFactoryService; } public KnowledgeBaseFactoryService getDroolsKnowledgeBaseFactoryService() { return droolsKnowledgeBaseFactoryService; } public void setDroolsKnowledgeBaseFactoryService( KnowledgeBaseFactoryService droolsKnowledgeBaseFactoryService) { this.droolsKnowledgeBaseFactoryService = droolsKnowledgeBaseFactoryService; } } Some of the bundles in my runtime are: 39 ACTIVE org.drools.core_5.4.0.Final 66 ACTIVE org.drools.compiler_5.4.0.Final 78 ACTIVE org.drools.templates_5.4.0.Final 94 ACTIVE org.drools.internalapi_5.4.0.Final 136 ACTIVE org.drools.decisiontables_5.4.0.Final 189 ACTIVE org.drools.api_5.4.0.Final 191 ACTIVE org.mvel2_2.1.0.drools16 6 ACTIVE org.jbpm.flow.core_5.3.0.Final 13 ACTIVE org.jbpm.bpmn2_5.3.0.Final 71 ACTIVE org.jbpm.flow.builder_5.3.0.Final 142 ACTIVE org.jbpm.flow-persistence-jpa_5.3.0.FINAL regards, Per Sterner