Microsoft .NET Framework 4.8
The October 15, 2019 update for Windows 8.1, RT 8.1, and Server 2012 R2 includes cumulative reliability improvements in .NET 4.8. 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 8.1, Windows RT 8.1, and Windows Server 2012 R2 require that update KB 2919355 is installed. We recommend that you install update KB 2919355 on your Windows 8.1-based, Windows RT 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
Addresses an issue with ValidationContext.MemberName when using custom DataAnnotation.ValidationAttribute.
Addresses and issue where software rendering fails to draw images whose position and scaling are too large. For example, an Image element with Width=10, sourced to a bitmap with width=500 and positioned 700 pixels from the left edge of the enclosing window, fails to appear because the scaling factor S = 500/10 = 50 and the position X=700 are too large, in the sense that their product S * X = 50 * 700 = 35000 exceeds 2^15 = 32768.
Reduces the risk of returning unordered ConstructorInfo's from Type.GetConstructors().
Improved behavior in scenarios where external bugs (such as a double-free) prevent underlying OS threads from starting. The runtime now fails with a diagnostic error rather than hanging waiting for the thread to start. This allows better failure recovery and better diagnostics of the problem that caused the failure.
Addresses and issue with late bound .NET COM calls containing SafeArrays where the SafeArray is not fully initialized.
Addresses an issue that prevented navigation to the last item of the dropped-down menu item by single up-arrow key press.
Addresses and issue where the property grid can throw a NullReferenceException when selection changes to null (nothing is selected) in response to value changes
1 Windows Presentation Foundation (WPF)
2 Common Language Runtime (CLR)
Additional information about this update
- 4520408 Description of the Preview of Quality Rollup for .NET Framework 3.5, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 for Windows 8.1, RT 8.1, and Server 2012 R2 (KB4520408)
Known Issues in this update
After applying this October 15th Preview of Quality Rollup for .NET Framework 4.8, some ClickOnce applications and applications creating the default AppDomain with a restricted permission set may observe application launch or application runtime failures, or unexpected behaviors. The observable issue is the System.AppDomainSetup.TargetFrameworkName (https://docs.microsoft.com/en-us/dotnet/api/system.appdomainsetup.targetframeworkname?view=netframework-4.8) is null, leading to any quirks enabling reverting back to .NET Framework 4.0 behaviors.
Customers observing new unexpected failures or functional issues can implement an application setting by adding (or merging) the following section to your application config file:
<?xml version="1.0" encoding="utf-8" ?>
How to obtain and install the update
Method 1: Windows Update
This update is available through Windows Update. Go to Settings > Update and Security > Windows Update, and then select Check for updates. For more information about how to get preview updates, see Windows Update: FAQ.
Method 2: Microsoft Update Catalog
To get the standalone package for this update, go to the Microsoft Update Catalog.
Method 3: Windows Software Update Services (WSUS)
On your WSUS server, follow these steps:
- Select Start, select Administrative Tools, and then select Microsoft Windows Server Update Services 3.0.
- Expand ComputerName, and then select Action.
- Select Import Updates.
- WSUS opens a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.
- After the ActiveX control is installed, you see the Microsoft Update Catalog screen. Type 4520408 into the Search box, and then select Search.
- Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Select Add to add them to your basket.
- After you select all the packages that you require, select View Basket.
- To import the packages to your WSUS server, select Import.
- After the packages are imported, select Close to return to WSUS.
The updates are now available for installation through WSUS.
To apply this update, you must have .NET Framework 4.8 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 updates 4516553.
Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2
The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed in the "Additional file information" section. MUM, MANIFEST, and the associated security catalog (.cat) files, are very important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
Additional file information