diff --git a/KInspector.Modules/Modules/Content/WorkflowConsistencyModule.cs b/KInspector.Modules/Modules/Content/WorkflowConsistencyModule.cs
index bbbafb6c..277a14c3 100644
--- a/KInspector.Modules/Modules/Content/WorkflowConsistencyModule.cs
+++ b/KInspector.Modules/Modules/Content/WorkflowConsistencyModule.cs
@@ -24,9 +24,9 @@ public ModuleMetadata GetModuleMetadata()
             return new ModuleMetadata
             {
                 Name = "Workflow consistency",
-                SupportedVersions = new[] { 
+                SupportedVersions = new[] {
                     new Version("7.0"),
-                    new Version("8.0"), 
+                    new Version("8.0"),
                     new Version("8.1"),
                     new Version("8.2"),
                     new Version("9.0") },
@@ -92,6 +92,12 @@ private List<ResultItem> FindDocumentsWithInconsistencies()
             {
                 var classItem = GetClassItem(document.ClassName);
 
+                if (!classItem.ClassIsDocumentType || !classItem.ClassIsCoupledClass)
+                {
+                    // Skip processing of document that has no coupled table
+                    continue;
+                }
+
                 // Get published data values
                 var publishedValues = GetDictionaryWithValues(classItem, document.DocumentForeignKeyValue);
 
@@ -227,13 +233,13 @@ private List<DocumentItem> GetDocuments()
             {
                 list.Add(new DocumentItem
                 {
-                    DocumentID = Convert.ToInt32(documentItem["DocumentID"]),
-                    DocumentName = documentItem["DocumentName"].ToString(),
-                    ClassName = documentItem["ClassName"].ToString(),
-                    DocumentForeignKeyValue = Convert.ToInt32(documentItem["DocumentForeignKeyValue"]),
+                    DocumentID = Convert.IsDBNull(documentItem["DocumentID"]) ? 0 : Convert.ToInt32(documentItem["DocumentID"]),
+                    DocumentName = documentItem["DocumentName"]?.ToString(),
+                    ClassName = documentItem["ClassName"]?.ToString(),
+                    DocumentForeignKeyValue = Convert.IsDBNull(documentItem["DocumentForeignKeyValue"]) ? 0 : Convert.ToInt32(documentItem["DocumentForeignKeyValue"]),
                     NodeXML = documentItem["NodeXML"].ToString(),
-                    NodeAliasPath = documentItem["NodeAliasPath"].ToString(),
-                    DocumentCulture = documentItem["DocumentCulture"].ToString()
+                    NodeAliasPath = documentItem["NodeAliasPath"]?.ToString(),
+                    DocumentCulture = documentItem["DocumentCulture"]?.ToString()
                 });
             }
 
@@ -242,7 +248,7 @@ private List<DocumentItem> GetDocuments()
 
         private void InitializeClassNames()
         {
-            var sql = "select ClassName, ClassFormDefinition, ClassTableName from CMS_Class where ClassIsDocumentType = '1'";
+            var sql = "select ClassName, ClassFormDefinition, ClassTableName, ClassIsCoupledClass, ClassIsDocumentType from CMS_Class";
             var result = InstanceInfo.DBService.ExecuteAndGetDataSet(sql);
 
             var list = new List<ClassItem>();
@@ -253,7 +259,9 @@ private void InitializeClassNames()
                 {
                     ClassName = classItem["ClassName"].ToString(),
                     TableName = classItem["ClassTableName"].ToString(),
-                    ClassFormDefinition = classItem["ClassFormDefinition"].ToString()
+                    ClassFormDefinition = classItem["ClassFormDefinition"].ToString(),
+                    ClassIsCoupledClass = Convert.ToBoolean(classItem["ClassIsCoupledClass"]),
+                    ClassIsDocumentType = Convert.ToBoolean(classItem["ClassIsDocumentType"]),
                 });
             }
 
@@ -301,6 +309,8 @@ private class DocumentItem
 
         private class ClassItem
         {
+            public bool ClassIsDocumentType { get; set; }
+            public bool ClassIsCoupledClass { get; set; }
             public string ClassName { get; set; }
             public string TableName { get; set; }
             public string ClassFormDefinition { get; set; }