diff --git a/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminCompletedInstancesPanel.java b/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminCompletedInstancesPanel.java
index 4384222d0f6a6120d8ef1789f7bbdb309c9a50a1..a7bd532431618ae38071b92e00d04221163bc2c8 100644
--- a/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminCompletedInstancesPanel.java
+++ b/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminCompletedInstancesPanel.java
@@ -152,6 +152,10 @@ public class AdminCompletedInstancesPanel extends DetailPanel {
 	      
 	      } else {
 	      	ProcessDefinition definition = repositoryService.createProcessDefinitionQuery().processDefinitionId(processDefinitionId).singleResult();
+	      	if (definition == null) {
+            // this process has a missing definition - skip
+            continue;
+          }
 	      	managementDefinition = new ManagementProcessDefinition();
 	      	managementDefinition.processDefinition = definition;
 	      	managementDefinition.runningInstances = new ArrayList<HistoricProcessInstance>();
diff --git a/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminRunningInstancesPanel.java b/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminRunningInstancesPanel.java
index eb2cd63145e2db6fa971ffd471fc0b22922169a6..3a8511e2efcc2371a0e0c66b026228cc11f90688 100644
--- a/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminRunningInstancesPanel.java
+++ b/modules/activiti-explorer/src/main/java/org/activiti/explorer/ui/management/admin/AdminRunningInstancesPanel.java
@@ -154,6 +154,10 @@ public class AdminRunningInstancesPanel extends DetailPanel {
 	      
 	      } else {
 	      	ProcessDefinition definition = repositoryService.createProcessDefinitionQuery().processDefinitionId(processDefinitionId).singleResult();
+	      	if (definition == null) {
+	      	  // this process has a missing definition - skip
+	      	  continue;
+	      	}
 	      	managementDefinition = new ManagementProcessDefinition();
 	      	managementDefinition.processDefinition = definition;
 	      	managementDefinition.runningInstances = new ArrayList<HistoricProcessInstance>();