This May 2017 Update for Windows 8.1 and Windows Server 2012 R2 includes cumulative reliability improvements in the .NET Framework 4.5.2. We recommend that you apply this update as part of your regular maintenance routines. Before you install this update, see the "Prerequisites" and "Restart requirement" sections.
- All updates for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 require update 2919355 to be installed. We recommend that you install update 2919355 on your Windows RT 8.1-based, Windows 8.1-based, or Windows Server 2012 R2-based computer so that you receive updates in the future.
- If you install a language pack after you install this update, you must reinstall this update. Therefore, we recommend that you install any language packs that you need before you install this update. For more information, see Add language packs to Windows.
Quality and reliability improvements
In the following scenarios, ASP.NET may duplicate the cookie in response headers:
Before a request cookie is loaded, the response cookie is added.
A response cookie is added, and then a native module sets the response cookie.
After you apply this fix, ASP.NET makes sure that response cookies are not duplicated.
ASP.NET sequentially executes requests that have the same SessionID, which means you may see requests piling up in the queue if there are lots of concurrent requests that have the same SessionID. After you apply this fix, you can limit the number of the requests in the queue by using the following AppSetting:
<appSettings> <add key="aspnet:RequestQueueLimitPerSession" value="50"/></appSettings>
If you marshal an array of struct A and also an array of struct B as SAFEARRAY, and struct A and B have identical GUIDs, a memory leak may occur.
In some cases, Windows Presentation Foundation (WPF) tries to process a touch or stylus input by using a null StylusDevice member. This can cause a NullReferenceException exception. This fix checks for this issue and guards against it.
A WPF application that uses a virtualizing list control (List Box, DataGrid, TreeView, or so on) can encounter an ArgumentNullException exception when you scroll to a list item whose size has greatly decreased since the last time that it was re-virtualized.
Note This update also contains cumulative updates that were released previously starting from October 11, 2016.
Additional information about this security update
For more information about this security update as it relates to Windows 8.1 and Windows Server 2012 R2, see the following article in the Microsoft Knowledge Base:
4019290 May 2017 Preview of the Quality Rollup for the .NET Framework 3.5, 4.5.2, 4.6, 4.6.1, and 4.6.2 updates for Windows 8.1 and Windows Server 2012 R2: May 16, 2017
How to get this update
This update is available from Windows Update, as an optional update.
To get the stand-alone package for this update, go to the Microsoft Update Catalog website.
To apply this update, you must have the .NET Framework 4.5.2 installed.
You must restart the computer after you apply this update if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this update.