Exchange mail sync fails with "value 'GroupMailbox' was not found" error

Using eM (v 7.2.37929.0) to connect to an exchange server via EWS.  I’ve been using eM for nearly two years for this server with no problem until now.

A few weeks ago, I began having failed connections with the error message “Requested value ‘GroupMailbox’ was not found”.  I’ve copied a log trace below for mail detail.   I have not had any problems connecting with my other clients (“9” on Android or Outlook 2016), only eM.

The problem has prevented me from updating email most of the time, but every now and then a connection succeeds and my inbox catches up.&nbsp; Looking over logs, I have determined (I think) that what is going on is this.&nbsp; &nbsp;When the exception is thrown, eM does first successfully obtain new message information from the server -- I can see all the headers and body text in the log.&nbsp; However, if any of the new messages contain the property " <mailboxtype>GroupMailbox</mailboxtype> ", the exception is thrown and no folders update.

If, from a different client, I delete all of the type=GroupMailbox new messages, and then clear them from the DeletedItems folder too, then eM will successfully update until a new GroupMailbox message appears in the queue, when it again fails.

Help would be appreciated.  This issue has made eM essentially useless for me.

****  LOG COPY ****

10:05:33.217|010|&nbsp; &nbsp;Exception: MailClient.Accounts.ConnectionException: Requested value 'GroupMailbox' was not found. ---\> System.ArgumentException: Requested value 'GroupMailbox' was not found.
10:05:33.217|010|&nbsp; &nbsp; &nbsp; at System.Enum.EnumResult.SetFailure(ParseFailureKind failure, String failureMessageID, Object failureMessageFormatArgument)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at System.Enum.TryParseEnum(Type enumType, String value, Boolean ignoreCase, EnumResult& parseResult)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at System.Enum.Parse(Type enumType, String value, Boolean ignoreCase)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.EwsUtilities.Parse[T](String value)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.EwsXmlReader.ReadElementValue[T]()
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.EmailAddress.TryReadElementFromXml(EwsServiceXmlReader reader)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ComplexProperty.InternalLoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName, Func`2 readAction)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ComplexProperty.LoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ComplexProperty.LoadFromXml(EwsServiceXmlReader reader, String xmlElementName)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ComplexPropertyCollection`1.LoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String localElementName)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ComplexPropertyCollection`1.LoadFromXml(EwsServiceXmlReader reader, String localElementName)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.InternalLoadFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.LoadPropertyValueFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.PropertyBag.LoadFromXml(EwsServiceXmlReader reader, Boolean clear, PropertySet requestedPropertySet, Boolean onlySummaryPropertiesRequested)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.EwsServiceXmlReader.ReadServiceObjectsCollectionFromXml[TServiceObject](XmlNamespace collectionXmlNamespace, String collectionXmlElementName, GetObjectInstanceDelegate`1 getObjectInstanceDelegate, Boolean clearPropertyBag, PropertySet requestedPropertySet, Boolean summaryPropertiesOnly)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.GetItemResponse.ReadElementsFromXml(EwsServiceXmlReader reader)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ServiceResponse.LoadFromXml(EwsServiceXmlReader reader, String xmlElementName)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.ParseResponse(EwsServiceXmlReader reader)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ReadResponse(EwsServiceXmlReader ewsXmlReader)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponseXml(Stream responseStream)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponse(IEwsHttpWebResponse response)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.Execute()
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ExchangeService.InternalLoadPropertiesForItems(IEnumerable`1 items, PropertySet propertySet, ServiceErrorHandling errorHandling)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at Microsoft.Exchange.WebServices.Data.ExchangeService.LoadPropertiesForItems(IEnumerable`1 items, PropertySet propertySet)
10:05:33.218|010|&nbsp; &nbsp; &nbsp; at MailClient.Protocols.Exchange.ExchangeItemSynchronizer`2.<changestoitems>d__18.MoveNext()<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at MailClient.Protocols.Common.ItemSynchronizeContext`2.<synchronize>g__FlushItems|13_0[T](Int32 threshold, &lt;&gt;c__DisplayClass13_0`1&amp; )<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at MailClient.Protocols.Common.ItemSynchronizeContext`2.Synchronize[T](SynchronizationType synchronizationType, IEnumerable`1 items, Func`2 getUniqueId, Func`3 hasChanged, Func`2 isDeleted, Func`2 convertItems, Action`2 updateItem)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at MailClient.Protocols.Exchange.ExchangeItemSynchronizer`2.Synchronize(IItemSynchronizeContext`1 synchronizeContext, Folder folder, CancellationToken cancellationToken)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at MailClient.Protocols.Common.ItemSynchronizer`2.&lt;&gt;c__DisplayClass32_0.<enqueuesynchronize>b__2(WorkerStatus status, CancellationToken cancellationToken)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      --- End of inner exception stack trace ---<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.218|010|      at MailClient.Commands.Command.Process(WorkerStatus status)<br alt="" name="" rel="" target="" title="" type="" value="">10:05:33.219|00A|   AccountBase.ChangeOnlineState : STATE CHANGE TO offline due BrokenConnection</enqueuesynchronize></synchronize></changestoitems>

There were some recent changes to Exchange server that caused a few issues, so maybe this is related. A fix was supplied in eM Client 7.2.38682 (or any later 7.2.x version), which you can download from the Release History.

Maybe give that a go and see if there is any difference.

Thanks! 

 I updated to 7.2.38715 and unfortunately there is no change in the behavior; same exception and failure to update mail

This may be fixed in the v8 beta.  Since the problem did intermittently vanish in v7 I’m not sure if its the new version or I’m just lucky tonight.  I’ll follow up in a day or two either way with a verdict.