KB4570721 – .NET Framework 4.8, 3.5 for Windows 10 2004

Microsoft releases cumulative update KB4571744 and .NET Framework KB4570721 for Windows 10 version 2004 users on 3rd Sept 2020. While KB4571744 (non-security) comes several bug fixes, KB4570721 is a regular patch that updates the existing .NET Framework on Windows 10 20H1.

Before applying this cumulative update, see the Prerequisites and Restart requirement sections first. We have also provided direct links to download this update for different system architectures. Let’s explore the KB4570721 patch in detail –


For Windows 10 1903 & 1909 Users:

KB4570723 .NET Framework 4.8, 3.5 Windows 10 1903 and 1909

KB4570721 .NET Framework 4.8, 3.5 Changelog

Here are the key highlights of this .NET framework update –

  • CLR: Resolves 32-bit apps related bug wherein JIT simply omit the function call. The company provided improved support to clean private as well as temporary certificate keys. 
  • WPF: Works upon the null-reference crash issue. This bug used to appear while reconnecting to a remote desktop automatically.
Quick Note: CLR stands for Common Language Runtime while WPF for  Windows Presentation Foundation.

KB4570721 Prerequisites

One must meet a few prerequisites before downloading/installing this .NET Framework. They are –

  • You must have a running .NET Framework 3.5 or 4.8 on your computer.

Restart requirements

  • Close all .NET Framework-based apps before applying this patch.
  • Restart Windows after applying this update.

How to Get the KB4570721 Optional update

Get the KB4570721 .NET Framework update for Windows 10 2004 following any of the two ways discussed below –

Note: Windows 10 2004 users may not get this patch via WSUS. However, they may manually import following these simple instructions.

1] Via Windows Update

  • Navigate to the path – Settings > Update & Security > Windows Update.
  • Move to the right side and click “Check for Updates“.
  • The system automatically looks for any pending updates.
  • If it finds any pending .NET Framework updates, downloads, and installs the same.
  • When your device prompts a notification, hit Restart Windows.

2] Through the Update Catalog

You may also use the direct link provided at the Update Catalog Site to download and install KB4570721. All you require is to follow these simple steps –

  • Head over to the Microsoft Update Catalog.
  • Once there, find the .NET Framework matching your system architecture i.e. x86, x64, or ARM64.
  • Click the Download button next to the patch displaying the correct system architecture.
  • On the upcoming wizard, hit the top link to start downloading the setup file.
  • Once over, go to the download folder and double click the downloaded file.
  • The system will take care of the remaining steps automatically. 

3] Direct Links

For simplicity, we have provided the direct links of the KB4570721 update below –

Release Note