July 13, 2021-KB5003539 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 10, version 1909

WPF₁

- Addresses an issue affecting a DataGrid contained in an outer ScrollViewer.

- Addresses a crash due to ElementNotAvailableException in a ListView with custom data-item automation peers.

CLR₂

- When the process is not under high memory pressure it tends to favor doing BGCs over doing full compacting GCs. This is usually desirable but if the app behavior changes dramatically, it could cause much of the fragmentation in older generations (ie, gen2 and LOH) to be unused. You can collect GC ETW events which tell you how much fragmentation there is in gen2 and LOH and verify if you are in this situation.

This version introduces a new GC config GCConserveMemory to detect this situation and be conservative about memory usage and not leave so much fragmentation unused.

You can specify it in the app.config file

<configuration>
  <runtime>
    <GCConserveMemory enabled="N"/>
  </runtime>
</configuration>

where N is an integer value between 0 and 9 (inclusive). 0 is the default. Not specifying this config or specifying it as 0 does not change GC tuning. Specifying a non zero value indicates to the GC how conservative you want GC to be about memory usage – the higher the value is, the more conservative GC will be, ie, the smaller the heap is. We suggest you to experiment with different numbers to see which value works best for you – usually we start with a value between 5 and 7. Note that if we detect LOH has too much fragmentation it will be compacted automatically.

Winforms

- Addresses an issue in Property Grid control to prevent incorrect data read in some scenarios in 64 bit processes.

- Addresses an issue where System.Drawing double frees allocated memory when failing to get printer settings.

ClickOnce

- Addresses a regression introduced in previous updates. We now honor WinTrust policy setting "Ignore timestamp revocation checks" setting when validating timestamps in ClickOnce manifests.

Release Channel

Available

Next Step

Windows Update and Microsoft Update

Yes

To download and install this update, go to Settings > Update & Security > Windows Update, and then select Check for updates.

Microsoft Update Catalog

Yes

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Windows Server Update Services (WSUS)

Yes

This update will automatically sync with WSUS if you configure Products and Classifications as follows:

Product: Windows 10, version 1909

Classification: Updates