Office 365 getting constant timeout and 404 errors only in EMClient.

Latest version is getting constant 404 and timeout errors accessing Office 365 directly from Microsoft on version 7.2.35595.0.  No such problems when using Outlook or Windows 10 Mail on the same account.

Me too.  The Log says this for me:  8:09:22 AM   MailClient.Storage.Application.OperationException: Synchronizing folder list failed due to the following error: The remote server returned an error: (404) Not Found. —> System.Net.WebException: The remote server returned an error: (404) Not Found.8:09:22 AM    at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
8:09:22 AM    at MailClient.Protocols.OfflineAddressBook.OabFolderSynchronizer.GetFolderList(Folder homeFolder, CancellationToken cancellationToken)
8:09:22 AM    at MailClient.Protocols.Common.FolderSynchronizer.<>c__DisplayClass10_0.b__0(WorkerStatus status, CancellationToken cancellationToken)
8:09:22 AM at MailClient.Protocols.OfflineAddressBook.OabGenericCommand.Execute(WorkerStatus status)

Now I’m also getting this:

5:13:54 PM MailClient.Accounts.ConnectionException: Requested value 'GroupMailbox' was not found. ---\> System.ArgumentException: Requested value 'GroupMailbox' was not found. 5:13:54 PM at System.Enum.EnumResult.SetFailure(ParseFailureKind failure, String failureMessageID, Object failureMessageFormatArgument) 5:13:54 PM at System.Enum.TryParseEnum(Type enumType, String value, Boolean ignoreCase, EnumResult& parseResult) 5:13:54 PM at System.Enum.Parse(Type enumType, String value, Boolean ignoreCase) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.EwsUtilities.Parse[T](String value) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.EwsXmlReader.ReadElementValue[T]() 5:13:54 PM at Microsoft.Exchange.WebServices.Data.EmailAddress.TryReadElementFromXml(EwsServiceXmlReader reader) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ComplexProperty.InternalLoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName, Func`2 readAction) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ComplexProperty.LoadFromXml(EwsServiceXmlReader reader, XmlNamespace xmlNamespace, String xmlElementName) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ComplexProperty.LoadFromXml(EwsServiceXmlReader reader, String xmlElementName) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.InternalLoadFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ContainedPropertyDefinition`1.InternalLoadFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ComplexPropertyDefinitionBase.LoadPropertyValueFromXml(EwsServiceXmlReader reader, PropertyBag propertyBag) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.PropertyBag.LoadFromXml(EwsServiceXmlReader reader, Boolean clear, PropertySet requestedPropertySet, Boolean onlySummaryPropertiesRequested) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.EwsServiceXmlReader.ReadServiceObjectsCollectionFromXml[TServiceObject](XmlNamespace collectionXmlNamespace, String collectionXmlElementName, GetObjectInstanceDelegate`1 getObjectInstanceDelegate, Boolean clearPropertyBag, PropertySet requestedPropertySet, Boolean summaryPropertiesOnly) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.GetItemResponse.ReadElementsFromXml(EwsServiceXmlReader reader) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ServiceResponse.LoadFromXml(EwsServiceXmlReader reader, String xmlElementName) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.ParseResponse(EwsServiceXmlReader reader) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ReadResponse(EwsServiceXmlReader ewsXmlReader) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponseXml(Stream responseStream) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.ReadResponse(IEwsHttpWebResponse response) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.Execute() 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ExchangeService.InternalBindToItems(IEnumerable`1 itemIds, PropertySet propertySet, ServiceErrorHandling errorHandling) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ExchangeService.BindToItem(ItemId itemId, PropertySet propertySet) 5:13:54 PM at Microsoft.Exchange.WebServices.Data.ExchangeService.BindToItem[TItem](ItemId itemId, PropertySet propertySet) 5:13:54 PM at MailClient.Protocols.Exchange.ExchangeCalendarSynchronizer.ConvertApplicationData(ExchangeService service, EventItem item, Func`2 getChildren) 5:13:54 PM at MailClient.Protocols.Exchange.ExchangeItemSynchronizer`2.Upload(IItemUploadContext`1 uploadContext, Folder folder, IEnumerable`1 items, CancellationToken cancellationToken) 5:13:54 PM at MailClient.Protocols.Common.ItemSynchronizer`2.\<\>c\_\_DisplayClass29\_0.<enqueueupload>b__0(WorkerStatus status, CancellationToken cancellationToken)
5:13:54 PM

 at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)
5:13:54 PM

 --- End of inner exception stack trace ---
5:13:54 PM

 at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)
5:13:54 PM

 at MailClient.Commands.Command.Process(WorkerStatus status) 
</enqueueupload>

What the heck happened to emClient?  It used to be rock solid!