diff --git a/jbpm-bpmn2/src/main/java/org/jbpm/bpmn2/xml/BoundaryEventHandler.java b/jbpm-bpmn2/src/main/java/org/jbpm/bpmn2/xml/BoundaryEventHandler.java
index 58d30e184b..e62428a2e6 100644
--- a/jbpm-bpmn2/src/main/java/org/jbpm/bpmn2/xml/BoundaryEventHandler.java
+++ b/jbpm-bpmn2/src/main/java/org/jbpm/bpmn2/xml/BoundaryEventHandler.java
@@ -59,7 +59,7 @@ public Object end(final String uri, final String localName,
         Node node = (Node) parser.getCurrent();
         String attachedTo = element.getAttribute("attachedToRef");
         Attr cancelActivityAttr = element.getAttributeNode("cancelActivity");
-        boolean cancelActivity = Boolean.parseBoolean(cancelActivityAttr.getValue());
+        boolean cancelActivity = cancelActivityAttr == null || Boolean.parseBoolean(cancelActivityAttr.getValue());
 
         // determine type of event definition, so the correct type of node can be generated
         org.w3c.dom.Node xmlNode = element.getFirstChild();
diff --git a/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/JpaProcessPersistenceContext.java b/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/JpaProcessPersistenceContext.java
index d9d74a90ae..8d85d02d9f 100644
--- a/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/JpaProcessPersistenceContext.java
+++ b/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/JpaProcessPersistenceContext.java
@@ -41,6 +41,7 @@
 public class JpaProcessPersistenceContext extends JpaPersistenceContext
     implements
     ProcessPersistenceContext {
+ 
     
     public JpaProcessPersistenceContext(EntityManager em, TransactionManager txm) {
         super( em, txm );
@@ -66,7 +67,10 @@ public PersistentProcessInstance findProcessInstanceInfo(Long processId) {
     	if( this.pessimisticLocking ) { 
             return em.find( ProcessInstanceInfo.class, processId, lockMode );
         }
-        return em.find( ProcessInstanceInfo.class, processId );
+        logger.trace("Reading process instance info {} with em {}", processId, em);
+        ProcessInstanceInfo pi = em.find(ProcessInstanceInfo.class, processId);
+        logger.trace("Process instance info read {}", pi);
+        return pi;
     }
 
     public void remove(PersistentProcessInstance processInstanceInfo) {
diff --git a/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/processinstance/ProcessInstanceInfo.java b/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/processinstance/ProcessInstanceInfo.java
index 723e4e672c..00696764e4 100644
--- a/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/processinstance/ProcessInstanceInfo.java
+++ b/jbpm-persistence/jbpm-persistence-jpa/src/main/java/org/jbpm/persistence/processinstance/ProcessInstanceInfo.java
@@ -55,11 +55,14 @@
 import org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl;
 import org.kie.api.runtime.Environment;
 import org.kie.api.runtime.process.ProcessInstance;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 @Entity
 @SequenceGenerator(name="processInstanceInfoIdSeq", sequenceName="PROCESS_INSTANCE_INFO_ID_SEQ")
 public class ProcessInstanceInfo implements PersistentProcessInstance {
 
+    private static final Logger logger = LoggerFactory.getLogger(ProcessInstanceInfo.class);
     @Id
     @GeneratedValue(strategy = GenerationType.AUTO, generator="processInstanceInfoIdSeq")
     @Column(name = "InstanceId")
@@ -192,9 +195,10 @@ public ProcessInstance getProcessInstance(InternalKnowledgeRuntime kruntime,
                 }
                 context.close();
             } catch ( IOException e ) {
-                e.printStackTrace();
-                throw new IllegalArgumentException( "IOException while loading process instance: " + e.getMessage(),
-                                                    e );
+                throw new IllegalArgumentException( "IOException while loading process instance: " + e.getMessage(), e);
+            } catch (RuntimeException e) {
+                logger.error("Error unmarshalling process instance info {}", processInstanceId, e);
+                throw e;
             }
         }
         ((WorkflowProcessInstanceImpl) processInstance).internalSetStartDate(this.startDate);
diff --git a/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/AbstractRuntimeManager.java b/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/AbstractRuntimeManager.java
index 75bfd2631e..09b487f164 100644
--- a/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/AbstractRuntimeManager.java
+++ b/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/AbstractRuntimeManager.java
@@ -83,6 +83,7 @@
 import org.kie.internal.runtime.manager.RuntimeManagerRegistry;
 import org.kie.internal.runtime.manager.SecurityManager;
 import org.kie.internal.runtime.manager.SessionFactory;
+import org.kie.internal.runtime.manager.SessionNotFoundException;
 import org.kie.internal.runtime.manager.TaskServiceFactory;
 import org.kie.internal.runtime.manager.context.ProcessInstanceIdContext;
 import org.kie.internal.runtime.manager.deploy.DeploymentDescriptorManager;
@@ -389,8 +390,8 @@ protected boolean canDispose(RuntimeEngine runtime) {
                     && tm.getStatus() != TransactionManager.STATUS_COMMITTED) {
                 return false;
             }
-        } catch (Exception e) {
-            logger.warn("Exception dealing with transaction", e);
+        } catch (SessionNotFoundException e) {
+            logger.warn("Session not found exception", e);
         }        
         return true;
     }
diff --git a/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/PerProcessInstanceRuntimeManager.java b/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/PerProcessInstanceRuntimeManager.java
index 19253e418e..dd46edd7c1 100644
--- a/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/PerProcessInstanceRuntimeManager.java
+++ b/jbpm-runtime-manager/src/main/java/org/jbpm/runtime/manager/impl/PerProcessInstanceRuntimeManager.java
@@ -19,6 +19,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.Objects;
 import java.util.Set;
 
@@ -198,10 +199,24 @@ public void signalEvent(String type, Object event) {
         
         // process currently active runtime engines
         Map<Object, RuntimeEngine> currentlyActive = local.get();
+
         if (currentlyActive != null && !currentlyActive.isEmpty()) {
-            RuntimeEngine[] activeEngines = currentlyActive.values().toArray(new RuntimeEngine[currentlyActive.size()]);
-            for (RuntimeEngine engine : activeEngines) {
-                Context<?> context = ((RuntimeEngineImpl) engine).getContext();
+            @SuppressWarnings("unchecked")
+            Entry<Object, RuntimeEngine> activeEngines[] = currentlyActive.entrySet()
+                    .toArray(new Entry[currentlyActive.size()]);
+            Set<Object> enginesToDelete = new HashSet<>();
+            for (Entry<Object, RuntimeEngine> engine : activeEngines) {
+                RuntimeEngineImpl engineImpl = (RuntimeEngineImpl) engine.getValue();
+                if (engineImpl==null) {
+                     continue;
+                }
+                if (engineImpl.isDisposed() || engineImpl.isInvalid()) {
+                    Object engineKey = engine.getKey();
+                    logger.trace("Engine with key {} is not longer valid", engineKey);
+                    enginesToDelete.add(engineKey);
+                    continue;
+                }
+                Context<?> context = engineImpl.getContext();
                 if (context != null && context instanceof ProcessInstanceIdContext 
                         && ((ProcessInstanceIdContext) context).getContextId() != null) {
                     try {