Prefetch Failed

Hi, I am getting the above error when syncing mail from outlook. Can anyone shed any light on this?

Is the account still syncing?

Most of the time, yes.

The problem is all over the place. I’m getting it and many of the systems I support are as well. Started a day or two ago … maybe as recently as yesterday. GoDaddy might be a common factor. (Anyone experiencing the error who doesn’t use GD will come right back and tell us that GD isn’t the culprit! Which would make a nice change.)

The prefetch error is an Exchange server error.

It can happen when you have set a folder or account for “offline use” and because of a server error, the cached data can’t be downloaded. Normal syncing should continue though.


Yes this is it. Tim Sussex probably sees this, and the ten or more people I know who started experiencing the error right out of the blue yesterday see it too.

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Thats it exactly and no, I don’t use GD - I have turned off the pop-up but the triangle still appears - annoying.

Got this just after sending a post containing a zipped attachment (3.68 mb). Happened when synchronising the “Sent” folder:

9:22:51 PM [email protected] Exchange Web Services Synchronizing folder ‘/Sent’
9:22:51 PM [email protected] Exchange Web Services Downloading messages: For folder /Sent

View the Log

9:22:53 PM mysite.com [Exchange Web Services] MailClient.Storage.Application.OperationException: Prefetch failed
—> Microsoft.Exchange.WebServices.Data.ServiceRequestException: The request failed. The operation was canceled.
—> System.Net.WebException: The operation was canceled.
—> System.Threading.Tasks.TaskCanceledException: The operation was canceled.
—> System.IO.IOException: Unable to read data from the transport connection: The I/O operation has been aborted because of either a thread exit or an application request…
—> System.Net.Sockets.SocketException (995): The I/O operation has been aborted because of either a thread exit or an application request.
— End of inner exception stack trace —
at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource<System.Int32>.GetResult(Int16 token)
at System.Net.Security.SslStream.EnsureFullTlsFrameAsync[TIOAdapter](TIOAdapter adapter)
at System.Net.Security.SslStream.ReadAsyncInternal[TIOAdapter](TIOAdapter adapter, Memory1 buffer) at System.Net.Http.HttpConnection.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken) --- End of inner exception stack trace --- at System.Net.Http.HttpClient.HandleFailure(Exception e, Boolean telemetryStarted, HttpResponseMessage response, CancellationTokenSource cts, CancellationToken cancellationToken, CancellationTokenSource pendingRequestsCts) at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken) at Microsoft.Exchange.WebServices.Data.EwsHttpWebRequest.GetResponse(CancellationToken token) --- End of inner exception stack trace --- at Microsoft.Exchange.WebServices.Data.EwsHttpWebRequest.GetResponse(CancellationToken token) at Microsoft.Exchange.WebServices.Data.EwsHttpWebRequest.GetResponse() at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request) --- End of inner exception stack trace --- at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request) at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ValidateAndEmitRequest(IEwsHttpWebRequest& request) at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest1.Execute()
at MailClient.Protocols.Exchange.ExchangeMailSynchronizer.GetItemContentInternal(Folder folder, IMailRepositoryItem item, IStoredMimePart basePart, String partName)
at MailClient.Protocols.Exchange.ExchangeMailSynchronizer.PrefetchItems(IPrefetchProgress progress, Folder folder, IEnumerable1 items, PrefetchType prefetchType, CancellationToken cancellationToken) --- End of inner exception stack trace --- at MailClient.Protocols.Exchange.ExchangeMailSynchronizer.PrefetchItems(IPrefetchProgress progress, Folder folder, IEnumerable1 items, PrefetchType prefetchType, CancellationToken cancellationToken)
at MailClient.Protocols.Common.ItemSynchronizer2.<>c__DisplayClass43_0.<EnqueuePrefetch>b__2(WorkerStatus status, CancellationToken cancellationToken1) at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status) at MailClient.Commands.Command.Process(WorkerStatus status) QueueIgnore = True EnqueuedStackTrace = at MailClient.Protocols.Common.ItemSynchronizer2.<>c__DisplayClass43_0.b__0()
at MailClient.Protocols.Common.AccountBase.RunIfOnline(Action actionIfOnline, Action actionIfOffline)
at MailClient.Protocols.Common.ItemSynchronizer2.EnqueuePrefetch(Folder folder, IEnumerable1 items, Int32 countEstimate, Int32 initialProgress, PrefetchType prefetchType, SynchronizationPriority priority, CancellationToken cancellationToken, Action1 completed) at MailClient.Protocols.Common.ItemSynchronizer2.<>c__DisplayClass40_2.b__6(WorkerStatus status, CancellationToken ct)
at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)
at MailClient.Commands.Command.Process(WorkerStatus status)
at MailClient.Commands.DefaultSynchronizationQueue.ThreadWorker(Object threadData)
at System.Threading.Thread.StartHelper.Callback(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.Thread.StartCallback()
GUIStatus_Exception_Reported = True

As I said above, the Exchange Prefetch error is a server error.

You will need to ask your email provider for assistance with it. But it shouldn’t interfere with normal use of eM Client. All it means is that when eM Client asks the server for data for offline use, the server returns an error. The result is if you use eM Client while not connected to the Internet, you may not be able to see your messages. While you wait for your email provider to fix this, to prevent the error showing, you can disable offline caching in Menu > Accounts> Exchange tab for the account.

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[Exchange Web Services] Prefetch failed

Is there any way to get more information, like what messages, or folder, is causing the issue? I feel if I want to report it to my email provider, they might want a little more information (and I have a huge number of folders and emails, going back to 2013)

Apologies, but what must our email service provider “fix”? This started after an emClient update. I need to give my Exchange service provider some detail of what to fix.

I need offline access so disabling this feature within emClient is not an option.