This August 2017 Update for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2 includes cumulative reliability improvements in the .NET Framework 3.5. 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
Very rarely, an instance of ReaderWriterLock may crash when releasing a lock. A new configuration variable is introduced to enable opting in to the fix. Set the environment variable COMPlus_ReaderWriterLock_UseFixedIdGeneration to 1 when you start the application to fix the issue.
Code was changed to make the setting of the permissions event-driven so that it could support changes in the option values.
Additional information about this update
For more information about this update as it relates to Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2, see the following article in the Microsoft Knowledge Base:
4035038 August 2017 Preview of the Quality Rollups for the .NET Framework 3.5, 4.5.2, 4.6, 4.6.1, 4.6.2, and 4.7 for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2: August 15, 2017
How to get this update
This update is available through Windows Update. When you turn on automatic updating, this update will be downloaded and installed automatically. For more information about how to get security updates automatically, see Windows Update: FAQ.
Microsoft Update Catalog
To get the stand-alone package for this update, go to the Microsoft Update Catalog website.
Windows Software Update Services (WSUS)
On your WSUS server, follow these steps:
- Click Start, click Administrative Tools, and then click Microsoft Windows Server Update Services 3.0.
- Expand ComputerName, and then click Action.
- Click Import Updates.
- WSUS will open a browser window in which you may be prompted to install an ActiveX control. Install the ActiveX control to continue.
- Once the ActiveX control is installed, you will see the Microsoft Update Catalog screen. Type 4035038 in the Search box, and then click Search.
- Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Click Add to add them to your basket.
- When you have selected all the packages you need, click View Basket.
- Click Import to import the packages to your WSUS server.
- Click Close once the packages have been imported to return to WSUS.
The updates are now available for installation through WSUS.
To apply this update, you must have the .NET Framework 3.5 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.
Update replacement information
This update replaces previously released update 4014598 that is dated May 16, 2017.