.NET Framework September 2017 Preview of Quality Rollup

Rich Lander [MSFT]

Today, we are releasing the September 2017 Preview of Quality Rollup. This type of rollup is intended for businesses that want to the preview or use quality improvements as soon as they are available.

This update applies to Windows 10 Update 1607 (Anniversary Update) and to Windows Server 2016.

FYI: The KBs for Windows Server 2016 have been delayed but will be available soon. This post will be updated when Windows Server 2016 KBs are available.

Quality and Reliability

This release contains the following quality and reliability improvements.


  • Silent bad codegen when optimizing expression. [460765]
  • Crash in Visual Studio due to race in CLR assembly loader. [462762]
  • Runtime underallocates arrays by one element in rare cases when jitting large methods. [463604]
  • AppContext feature opt-in/out not functioning correctly. [469020]


  • HTTPWebRequest times out when switching to TLS after installing update KB4019112. [465796]

Windows Forms

  • Multi-Mon support: Controls with non-default anchoring are moved around the screen when scaling is changed [462872].


  • WPF consumes high % of CPU in Visual Studio when console session not active. [391184]
  • Application crash due to call into DWrite. [453529]

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 commentsor 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 4038801
.NET Framework 4.6.2 and 4.7 4038801

Previous Rollups and Updates

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


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