.NET Framework June 2021 Cumulative Update Preview

Tara Overfield

Earlier this week, we released the June 2021 Cumulative Update Preview for .NET Framework for Windows 10, version 2004, Windows Server 2004, Windows 10, version 20H2, Windows Server 20H2, and Windows 10, version 21H1.

Quality and Reliability

This release contains the following quality and reliability improvements.

  • Addresses a regression introduced in previous updates. We now honor WinTrust policy setting “Ignore timestamp revocation checks” setting when validating timestamps in ClickOnce manifests.
  • 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.
Windows Forms
  • 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.
  • 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.

1 Common Language Runtime (CLR)
2 Windows Presentation Foundation (WPF)

Getting the Update

The Cumulative Update Preview is available via Windows Update and Microsoft Update Catalog.

Microsoft Update Catalog

You can get the update via the Microsoft Update Catalog.

**Note**: Customers that rely on Windows Update and Windows Server Update Services will automatically receive the .NET Framework version-specific updates. Advanced system administrators can also take use of the below direct Microsoft Update Catalog download links to .NET Framework-specific updates. Before applying these updates, please ensure that you carefully review the .NET Framework version applicability, to ensure that you only install updates on systems where they apply.

The following table is for Windows 10 and Windows Server 2016+ versions.

Product Version Cumulative Update
Windows 10 21H1
.NET Framework 3.5, 4.8 Catalog 5003537
Windows 10, version 20H2 and Windows Server, version 20H2
.NET Framework 3.5, 4.8 Catalog 5003537
Windows 10 2004 and Windows Server, version 2004
.NET Framework 3.5, 4.8 Catalog 5003537


Previous Monthly Rollups

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


Discussion is closed. Login to edit/delete existing comments.

  • Dean Jackson 0

    Please explain what you mean by “Preview”. Does it mean that after some time, that a non-preview one of the same version will come to Windows Update?


    • Mystery Man 0

      Yes, exactly that. **Preview** doesn’t even mean “in beta”. It just means ahead of schedule.

      And let me clarify what “schedule” means.

      • I download their 11 May 2021 update; it was digitally signed on 11 February 2021, one day after their February update was released.
      • Their earlier 8 June 2021 update? It was digitally signed in April.
      • This update? It was digitally signed on 15 May 2021.
      • Tara OverfieldMicrosoft employee 0

        .NET Framework releases updates to some OSes as optional updates in advance of releasing them to all customers as recommended. This June Preview is a early availability of what is scheduled to be released in early July. The signing date that you notice is because the .NET Framework servicing team creates the updates in advance of release date. The signing date is roughly aligned when updates are created.

  • Terry Hulseberg 0

    I have multiple Win10 64-bit pro systems that update to this release. One of them immediately stopped working. I found there was 495GB used and only 5GB free indicated. This system only has 1 task and just a handful of programs loaded. I cannot find more than about 250GB used. THEN I discovered the C: drive has been encrypted by bitlocker. Apparently this is causing the drive to think it’s FULL as I keep getting that error and it just acts like it.

    Update history shows this .NET update being installed on the exact day the problems started.

    I have turned off bitlocker and am currently decrypting the C: which looks like it going to take all day. WHAT THE HECK? AM I DOING THE RIGHT THING?

    4 hours later, hardly any progress on decryption. manage=bde -status c: says protection off, decryption in=progress.

    • Tara OverfieldMicrosoft employee 0

      Thanks for dropping a comment and sorry to hear about the drive-related issues. .NET Framework updates will not and can not make any system level changes to your logical drives and their encryption and/or bit-locker status.

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