Compilation error argument null exception

I just received this error what do i need to correct this?

Code:

[Error] Compilation error:  (ArgumentNullException: Argument cannot be null.
Parameter name: obj)
8:10 AM [Stacktrace]   at System.Runtime.Serialization.ObjectIDGenerator.GetId (System.Object obj, System.Boolean& firstTime) [0x00000] in <filename unknown>:0
  at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.WriteObjectInstance (System.IO.BinaryWriter writer, System.Object obj, Boolean isValueObject) [0x00000] in <filename unknown>:0
  at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.WriteQueuedObjects (System.IO.BinaryWriter writer) [0x00000] in <filename unknown>:0
  at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.WriteObjectGraph (System.IO.BinaryWriter writer, System.Object obj, System.Runtime.Remoting.Messaging.Header[] headers) [0x00000] in <filename unknown>:0
  at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize (System.IO.Stream serializationStream, System.Object graph, System.Runtime.Remoting.Messaging.Header[] headers) [0x00000] in <filename unknown>:0
  at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize (System.IO.Stream serializationStream, System.Object graph) [0x00000] in <filename unknown>:0
  at ObjectStream.IO.ObjectStreamWrapper`2[ObjectStream.Data.CompilerMessage,ObjectStream.Data.CompilerMessage].Serialize (ObjectStream.Data.CompilerMessage obj) [0x00000] in <filename unknown>:0
  at ObjectStream.IO.ObjectStreamWrapper`2[ObjectStream.Data.CompilerMessage,ObjectStream.Data.CompilerMessage].WriteObject (ObjectStream.Data.CompilerMessage obj) [0x00000] in <filename unknown>:0
  at ObjectStream.ObjectStreamConnection`2[ObjectStream.Data.CompilerMessage,ObjectStream.Data.CompilerMessage].WriteStream () [0x00000] in <filename unknown>:0
  at ObjectStream.Threading.Worker.DoWorkImpl (System.Object oAction) [0x00000] in <filename unknown>:0