The process cannot access the file because it is being used by another process.

[Chris]

Is anyone else getting this problem with a basic AsyncUpload upload, we have started to get this exception a lot since a windows update was installed:

https://support.microsoft.com/en-gb/help/4032115/july-2017-preview-of-the-quality-rollups-for-the-net-framework-3-5-4-5

It does not seem to be telerik version specific as this is affecting websites using the old DLL too.

The call stack is as follows:

==

System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.IO.IOException: The process cannot access the file because it is being used by another process. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.File.InternalMove(String sourceFileName, String destFileName, Boolean checkHost) at popup_AddBulkFiles.RadButtonSaveFile_Click(Object sender, EventArgs e) at Telerik.Web.UI.RadButton.OnClick(ButtonClickEventArgs e) at Telerik.Web.UI.RadButton.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.HandleError(Exception e) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest() at System.Web.UI.Page.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

==

Also more seriously it seems to be corrupting files uploaded too e.g. a chunk of a file which was at the beginning is being duplicated in the middle.

I would report this as a bug but I have not been able to replicate it from my end.

Thanks

[Marin Bratanov]

Hi Chris,

If you manage to replicate this in a simple solution, do send it over so we can have a look and hopefully see how this update is related.

In the meantime I can suggest removing the update from the server.

I am also pinning this thread to the top of the forum so it gets more attention in case more people experience such a breaking change and this gets reported to MS (and hopefully fixed).

Regards,

Marin Bratanov
Progress Telerik

[Chris]

The Microsoft patch has been uninstalled and everything is back to normal again.

I contacted some of the users with corrupted files the only common trend was they all used the latest version of Firefox and the uploaded file was always bigger than the actual file using a hex compare of several files the initial header of the file was repeated for no obvious reason in the middle of the file hence why it was bigger.

Confident its nothing to do with telerik as different sites had different version of the DLL and they were all affected, although a normal 'FileUpload' control did not appear to have any issues.

[Marin Bratanov]

That's good to hear Chris.

My best guess at the moment is that this update breaks something in the way .NET works with streams/files and this, in turn, breaks the chunk upload which creates a number of streams and files for each chunk and then combines them into one file when the last piece arrives.

--Marin