Help with Workflow exception

Question

Here is the stack trace of exception I get when workflow is persisted .

System.Workflow.Runtime.Hosting.PersistenceException: Type 'System.Xml.XmlElement' in Assembly 'System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' is not marked as serializable. ---> System.Runtime.Serialization.SerializationException: Type 'System.Xml.XmlElement' in Assembly 'System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' is not marked as serializable.
   at System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type)
   at System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context)
   at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo()
   at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter)
   at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.Serialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter)
   at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph)
   at System.Workflow.ComponentModel.Activity.Save(Stream stream, IFormatter formatter)
   at System.Workflow.ComponentModel.Activity.Save(Stream stream)
   at System.Workflow.Runtime.Hosting.WorkflowPersistenceService.GetDefaultSerializedForm(Activity activity)
   at System.Workflow.Runtime.Hosting.SqlWorkflowPersistenceService.SaveWorkflowInstanceState(Activity rootActivity, Boolean unlock)
   at System.Workflow.Runtime.WorkflowExecutor.Persist(Activity dynamicActivity, Boolean unlock, Boolean needsCompensation)
   --- End of inner exception stack trace ---
   at System.Workflow.Runtime.WorkflowExecutor.Persist(Activity dynamicActivity, Boolean unlock, Boolean needsCompensation)
   at System.Workflow.Runtime.WorkflowExecutor.ProtectedPersist(Boolean unlock)

I have no Idea how and where to debug. Please help.

Answer 1

Are you using the SQL persister?

Answer 2

The error message tells you right at the top:

'System.Xml.XmlElement' in Assembly 'System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' is not marked as serializable.

When a workflow is persisted the WorkflowPersistenceService uses the binary serializer to dump all the data in the workflow. So everything in there must be either marked as non serializable or must be binary serializble. An XmlElement isn't so you must either store the data in some other way or not save it at all.