.NET Framework August 2017 Preview of Quality Rollup

Rich Lander [MSFT]

The August 2017 Preview of Quality Rollup is now available.

Quality and Reliability

This release contains the following quality and reliability improvements.


  • Values added to System.Web.Cache expire immediately, with .NET Framework 4.7. [452228]
  • ASP.NET site running on Sitefinity broken, with .NET Framework 4.7. [457739]


  • CRWLock::StaticAcquireWriterLock() never returns if Int32.MaxValue number of ReaderWriterLock objects are created, with .NET Framework 3.5. [242568]
  • Crash in Visual Studio due to race in CLR assembly loader. [462762]
  • .NET remoting IPC listener thread exits and leaves an orphaned IPCServerchannel. [454409]
  • Crash in CLR assembly metadata reader. [367294]


  • Reboot method of Win32_OperatingSystem has Privilege not held exception [441901]

Windows Forms

  • Excessive object creation in a performance-critical code-path leading to performance regressions and/or displaying empty UI and/or exhausting GDI+ handles. [452048]


  • NetTcp with X509Certificates using SslStream uses the default TLS version as the OS, with .NET Framework 4.7. [451528]


  • Handle(event) leaks with WPF application on touch screen monitors. [398137]
  • TargetFrameworkName is null with mixed mode application. [425074]
  • Visual Studio fails due to “Unable to load DLL ‘PenIMC.dll'” error. [452476]
  • WPF fails to load resources if two versions of the same assembly are loaded. [378607]

Note: Additional information on these improvements is not available. The VSTS bug number provided with each improvement is a unique ID that you can give Microsoft Customer Support, include in StackOverflow comments or use in web searches.

Getting the Update

The Preview of Quality Rollup is available via Windows Update, Windows Server Update Services and Microsoft Update Catalog.

Downloading KBs from Microsoft Update Catalog

You can download patches from the table below. See .NET Framework Monthly Rollups Explained for an explanation on how to use this table to download patches from Microsoft Update Catalog.

Product Version Preview of Quality Rollup KB
Windows 10 Update 1607 Windows Server 2016 Catalog 4034661
.NET Framework 3.5 4034661
.NET Framework 4.6.2 and 4.7 4034661
Windows 8.1 Windows RT 8.1 Windows Server 2012 R2 Catalog 4035038
.NET Framework 3.5 4033997
.NET Framework 4.5.2 4033991
.NET Framework 4.6, 4.6.1, 4.6.2, 4.7 4033989
Windows Server 2012 Catalog 4035037
.NET Framework 3.5 4033995
.NET Framework 4.5.2 4033992
.NET Framework 4.6, 4.6.1, 4.6.2, 4.7 4033988
Windows 7 Windows Server 2008 R2 Catalog 4035036
.NET Framework 3.5.1 4033996
.NET Framework 4.5.2 4033993
.NET Framework 4.6, 4.6.1, 4.6.2, 4.7 4033990
Windows Server 2008 Catalog 4035039
.NET Framework 2.0 4033994
.NET Framework 4.5.2 4033993
.NET Framework 4.6 4033990

Known Issues

Incorrect text in .NET Framework Setup

  • .NET Framework versions: 4.5.2
  • Windows versions: Windows 7, Windows Server 2008, Windows Server 2008 R2
  • Affected KBs: KB4033993

When you apply this update on non-English locale systems, you may notice some pseudo localized characters instead of localized content in the interactive setup. This is a non-impacting, UI-only, setup issue that does not affect the deployment result or functionality of the update contents. Please apply this update to help secure your computer against vulnerabilities and the issues that are addressed by this update. For more information, see: KB 4043564.

File Version is not Updated

The File Version of the following files did not change in this update.

  • System.Management.dll
  • WMINet_Utils.dll

It is typical for both File Version and Date Modified fields to be unique in each update. The unique values helps for identification of patches.

You can see these fields in the file properties for System.Management.dll, for example, in the following image.

File Properties for System.Management.dll

Previous Rollups and Updates

The last few .NET Framework Monthly updates are listed below for your convenience:


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