Internal ArgumentOutOfRangeException in EWS Managed API

Dear Microsoft,

We’ve been happily using the EWS Managed API for one of our products, but recently ran into an obscure problem with it.

While forwarding e-mails always used to work flawlessly, we recently started getting the following, strange error at a client site: an ArgumentOutOfRangeException in some get_Item() method over 20 layers deep in the call stack.

 Microsoft.Exchange.WebServices.dll version number: 15.0.516.14

The stacktrace:

System.ArgumentOutOfRangeException: index is out of range.
Parameter name: index
   at Microsoft.Exchange.WebServices.Data.ComplexPropertyCollection`1.get_Item(Int32 index)
   at Microsoft.Exchange.WebServices.Data.ComplexPropertyCollection`1.UpdateFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName)
   at Microsoft.Exchange.WebServices.Data.ComplexProperty.UpdateFromXml(EwsServiceXmlReader reader, String xmlElementName)
   at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.InternalLoadFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag)
   at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.LoadPropertyValueFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag)
   at Microsoft.Exchange.WebServices.Data.PropertyBag.LoadFromXml(EwsServiceXmlReader reader, Boolean clear, PropertySet requestedPropertySet, Boolean onlySummaryPropertiesRequested)
   at Microsoft.Exchange.WebServices.Data.ItemAttachment.TryReadElementFromXmlToPatch(EwsServiceXmlReader reader)
   at Microsoft.Exchange.WebServices.Data.ComplexProperty.InternalLoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName, Func`2 readAction)
   at Microsoft.Exchange.WebServices.Data.ComplexProperty.UpdateFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName)
   at Microsoft.Exchange.WebServices.Data.ComplexPropertyCollection`1.UpdateFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName)
   at Microsoft.Exchange.WebServices.Data.ComplexProperty.UpdateFromXml(EwsServiceXmlReader reader, String xmlElementName)
   at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.InternalLoadFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag)
   at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.LoadPropertyValueFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag)
   at Microsoft.Exchange.WebServices.Data.PropertyBag.LoadFromXml(EwsServiceXmlReader reader, Boolean clear, PropertySet requestedPropertySet, Boolean onlySummaryPropertiesRequested)
   at Microsoft.Exchange.WebServices.Data.EwsServiceXmlReader.ReadServiceObjectsCollectionFromXml[TServiceObject](XmlNamespace collectionXmlNamespace, String collectionXmlElementName, GetObjectInstanceDelegate`1 getObjectInstanceDelegate, Boolean clearPropertyBag, PropertySet requestedPropertySet, Boolean summaryPropertiesOnly)
   at Microsoft.Exchange.WebServices.Data.CreateItemResponseBase.ReadElementsFromXml(EwsServiceXmlReader reader)
   at Microsoft.Exchange.WebServices.Data.ServiceResponse.LoadFromXml(EwsServiceXmlReader reader, String xmlElementName)
   at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.ParseResponse(EwsServiceXmlReader reader)
   at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ReadResponse(EwsServiceXmlReader ewsXmlReader)
   at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponseXml(Stream responseStream)
   at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponse(IEwsHttpWebResponse response)
   at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.Execute()
   at Microsoft.Exchange.WebServices.Data.ExchangeService.InternalCreateItems(IEnumerable`1 items, FolderId parentFolderId, Nullable`1 messageDisposition, Nullable`1 sendInvitationsMode, ServiceErrorHandling errorHandling)
   at Microsoft.Exchange.WebServices.Data.Item.InternalCreate(FolderId parentFolderId, Nullable`1 messageDisposition, Nullable`1 sendInvitationsMode)
   at Microsoft.Exchange.WebServices.Data.EmailMessage.InternalSend(FolderId parentFolderId, MessageDisposition messageDisposition)
   at Microsoft.Exchange.WebServices.Data.EmailMessage.SendAndSaveCopy()

 

The code that triggers it:

ExtendedPropertyDefinition pr_flags =newExtendedPropertyDefinition(3591,MapiPropertyType.Integer);

itemAttachment.Item.SetExtendedProperty(pr_flags,"1");

itemAttachment.Name = originalEwsMailObject.Subject;

bodyBuilder.AppendLine("[product name etc. snipped]   forwarded because: \r\n\r\n"+ reason);

myMail.Body = bodyBuilder.ToString();

myMail.ToRecipients.Add(adminAddress);

myMail.SendAndSaveCopy();

Does anyone know how to solve this, or is it perhaps a bug in the API and should I report it somewhere?

Kind regards, 

Tom Kersbergen
Docspo B.V.