October 15, 2019
.NET Framework 4.8
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)
Known Issues in this update
After applying this October 15th Cumulative Update 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
Install this update
To download and install this update, go to Settings > Update & Security > Windows Update, and then select Check for updates.
To get the standalone package for this update, go to the Microsoft Update Catalog website.
For a list of the files that are provided in this update, download the file information for cumulative update .
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 4515842.