Win Update KB5064401 Cumulative Update .NET Framework 3.5 and 4.8.1 (24H2) - Sep. 9



 Microsoft Support:

August 28, 2025 - KB5064401 Cumulative Update for .NET Framework 3.5 and 4.8.1 for Windows 11, version 24H2​

IMPORTANT

This update was originally released in the Security and Quality Rollup that’s dated August 26, 2025. This update is included in the Security and Quality Rollup that’s dated September 9, 2025. There is no change to this update with this release on September 9, 2025. If you have previously installed this update no action is needed.


The August 28, 2025 update for Windows 11, version 24H2 includes security and cumulative reliability improvements in .NET Framework 3.5 and 4.8.1. 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.

Summary

Security Improvements
There are no new security improvements in this release. This update is cumulative and contains all previously released security improvements.

Quality and Reliability Improvements

ASP.NET- Addressed an issue in ASP.NET where some error events fail to log properly in the Windows Event log.
WPF 1-Addressed an update for GB18030 certificate for Chinese language changes.
1 Windows Presentation Foundation (WPF)

Known issues in this update

Microsoft is not currently aware of any issues in this update.

How to get this update

Install this update

Release ChannelAvailableNext Step
Windows Update and Microsoft UpdateYesGo to Settings > Update & Security > Windows Update. In the Optional updates available area, you’ll find the link to download and install the update.
Windows Update for BusinessYesGo to Settings > Update & Security > Windows Update. In the Optional updates available area, you’ll find the link to download and install the update.
Microsoft Update CatalogYesTo get the standalone package for this update, go to the Microsoft Update Catalog website.
Windows Server Update Services (WSUS)NoYou can import this update into WSUS manually. See the Microsoft Update Catalog for instructions.

File information

For a list of the files that are provided in this update, download the file information for cumulative update.

Prerequisites

To apply this update, you must have .NET Framework 3.5 or 4.8.1 installed.

Restart requirement

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.


 Source:

 
Last edited:
Downloading it...

1756503081776.webp
 

My Computer

System One

  • OS
    Windows 11
    Computer type
    PC/Desktop
    Manufacturer/Model
    Asus/Custom Build
    CPU
    Intel® Xeon® X5690 3.47GHz Six-Core
    Motherboard
    Asus P6T Deluxe v2
    Memory
    G.Skill PC3-12800 1600MHz 24GB
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    NVIDIA GeForce GTX 1050
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    SoundMAX ADI AD2000B HD Audio
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    Acer T232HL Touch Screen
    Screen Resolution
    1920 x 1080 @ 60Hz
    Hard Drives
    6 Crucial MX500 SSD 1TB each.
    PSU
    Thermaltake Toughpower Gold 850W
    Case
    Thermaltake Armor VA8000SWA
    Cooling
    Thermaltake Air Cooling System
    Keyboard
    Illuminated Multimedia LED Keyboard
    Mouse
    M16 Dual Mode Illuminated Mouse - Bluetooth / 2.4 GHz Mode
    Internet Speed
    800 Mbps
    Browser
    Edge / Opera / Vivaldi / Chrome / Firefox / Brave
    Antivirus
    Windows Defender Security
Installed fine!

1756503446300.webp
 

My Computer

System One

  • OS
    Windows 11
    Computer type
    PC/Desktop
    Manufacturer/Model
    Asus/Custom Build
    CPU
    Intel® Xeon® X5690 3.47GHz Six-Core
    Motherboard
    Asus P6T Deluxe v2
    Memory
    G.Skill PC3-12800 1600MHz 24GB
    Graphics Card(s)
    NVIDIA GeForce GTX 1050
    Sound Card
    SoundMAX ADI AD2000B HD Audio
    Monitor(s) Displays
    Acer T232HL Touch Screen
    Screen Resolution
    1920 x 1080 @ 60Hz
    Hard Drives
    6 Crucial MX500 SSD 1TB each.
    PSU
    Thermaltake Toughpower Gold 850W
    Case
    Thermaltake Armor VA8000SWA
    Cooling
    Thermaltake Air Cooling System
    Keyboard
    Illuminated Multimedia LED Keyboard
    Mouse
    M16 Dual Mode Illuminated Mouse - Bluetooth / 2.4 GHz Mode
    Internet Speed
    800 Mbps
    Browser
    Edge / Opera / Vivaldi / Chrome / Firefox / Brave
    Antivirus
    Windows Defender Security
I received 4401 on the 14th and 4402 today.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro
    Computer type
    PC/Desktop
    Manufacturer/Model
    Self Built
    CPU
    Intel Core i9 14900k, Intel UHD 770 integrated
    Motherboard
    Gigabyte Z790 Aorus Master X
    Memory
    32gb G.Skill Trident Z5 7200
    Graphics Card(s)
    Gigabyte RTX 4090 Gaming OC
    Sound Card
    EVGA Nu Audio, Razer Kraken V3 Pro, Realtek Onboard
    Monitor(s) Displays
    Dell U4025QW nano IPS monitor, Samsung Odyssey G75F, Wisecoco 12.6" IPS sensor panel
    Screen Resolution
    5120X2160 x 2 1920x515
    Hard Drives
    WD Black SN8100, Samsung 990 Pro x 3, WD BLACK SN850x, WD Black 8tb HD
    PSU
    FSP Hydro PTM Pro 1350w
    Case
    Thermaltake Level 20 XT
    Cooling
    ARCTIC Liquid Freezer III 420 ARGB in push/pull, Antec Prism X 120mm ARGB Fans x 15
    Keyboard
    Razer Blackwidow V4 Pro
    Mouse
    Razer Basilik V3 Pro on Razer Firefly V2 mouse pad.
    Internet Speed
    950 Mbps cable primary, 6Mbps secondary vdsl
    Browser
    Chrome primary, FF-Edge-IE secondary
    Antivirus
    Norton 360 Premium
    Other Info
    I sit on a Libernovo Omni chair.😍 Sound by Fosi Audio DA-2120C pushing Magnat Series 503 bookshelf speakers and a SVS SB-1000 Pro subwoofer.
  • Operating System
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    2023 Acer Predator Helios 18
    CPU
    Intel 14900HX
    Motherboard
    factory
    Memory
    32gb ddr 5 5600
    Graphics card(s)
    Nvidia RTX 4090 mobile
    Sound Card
    onboard
    Monitor(s) Displays
    18" 250hz IPS
    Screen Resolution
    2560X1600
    Hard Drives
    Samsung 9100 Pro, 990 Pro
    PSU
    factory 330W
    Case
    factory
    Cooling
    factory
    Keyboard
    individual key argb
    Mouse
    touchpad
    Internet Speed
    WiFi 7, 2.5gb ethernet
    Browser
    Chrome primary, FF-IE and Edge secondary
    Antivirus
    Norton 360 Premium
    Other Info
    Acer will not allow WD Black SN8100 to function in m.2 slot 0 and Crucial T710 ssd's to function in either slot.
Now out of preview.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro for Workstations
    Computer type
    PC/Desktop
    Manufacturer/Model
    Custom self build
    CPU
    Intel i7-8700K 5 GHz
    Motherboard
    ASUS ROG Maximus XI Formula Z390
    Memory
    64 GB (4x16GB) G.SKILL TridentZ RGB DDR4 3600 MHz (F4-3600C18D-32GTZR)
    Graphics Card(s)
    ASUS ROG-STRIX-GTX1080TI-O11G-GAMING (11GB GDDR5X)
    Sound Card
    Integrated Digital Audio (S/PDIF)
    Monitor(s) Displays
    2 x Samsung Odyssey G75 27"
    Screen Resolution
    2560x1440
    Hard Drives
    1TB Samsung 990 PRO M.2,
    4TB Samsung 990 PRO M.2,
    TerraMaster F8 SSD Plus NAS
    PSU
    Seasonic Prime Titanium 850W
    Case
    Thermaltake Core P3 wall mounted
    Cooling
    Corsair Hydro H115i
    Keyboard
    Amazon Basics Wired Full Keyboard MD005
    Mouse
    Logitech MX Master 4
    Internet Speed
    2 Gbps Download and 100 Mbps Upload
    Browser
    Chrome and Edge
    Antivirus
    Microsoft Defender
    Other Info
    Logitech Z625 speaker system,
    Logitech BRIO 4K Pro webcam,
    HP Color LaserJet Pro MFP M477fdn,
    CyberPower CP1500PFCLCD
    Galaxy S23 Plus phone
  • Operating System
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    Surface Laptop 7 Copilot+ PC
    CPU
    Snapdragon X Elite (12 core) 3.42 GHz
    Memory
    16 GB LPDDR5x-7467 MHz
    Monitor(s) Displays
    15" HDR
    Screen Resolution
    2496 x 1664
    Hard Drives
    1 TB SSD
    Internet Speed
    Wi-Fi 7 and Bluetooth 5.4
    Browser
    Chrome and Edge
    Antivirus
    Microsoft Defender

My Computer

System One

  • OS
    Windows 11
@Brink and anyone else really,
could you please clarify the situation a little for me?

What is the latest version of Cumulative Update .NET Framework 3.5 and 4.8.1
for 24H2 and 25H2?

Based on Microsoft Update Catalog

there is KB5064401 for 24H2
KB5064401 Info
(KB5064401 support page)

and there is KB5066613 for 25H2
KB5066613 Info
(although https://support.microsoft.com/help/5066613 is dead at the moment).

Is that correct?

Thanks in advance.

Hello, :alien:

KB5064401 is the latest for 24H2.

25H2 is still only officially available in the Insider Release Preview channel.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro for Workstations
    Computer type
    PC/Desktop
    Manufacturer/Model
    Custom self build
    CPU
    Intel i7-8700K 5 GHz
    Motherboard
    ASUS ROG Maximus XI Formula Z390
    Memory
    64 GB (4x16GB) G.SKILL TridentZ RGB DDR4 3600 MHz (F4-3600C18D-32GTZR)
    Graphics Card(s)
    ASUS ROG-STRIX-GTX1080TI-O11G-GAMING (11GB GDDR5X)
    Sound Card
    Integrated Digital Audio (S/PDIF)
    Monitor(s) Displays
    2 x Samsung Odyssey G75 27"
    Screen Resolution
    2560x1440
    Hard Drives
    1TB Samsung 990 PRO M.2,
    4TB Samsung 990 PRO M.2,
    TerraMaster F8 SSD Plus NAS
    PSU
    Seasonic Prime Titanium 850W
    Case
    Thermaltake Core P3 wall mounted
    Cooling
    Corsair Hydro H115i
    Keyboard
    Amazon Basics Wired Full Keyboard MD005
    Mouse
    Logitech MX Master 4
    Internet Speed
    2 Gbps Download and 100 Mbps Upload
    Browser
    Chrome and Edge
    Antivirus
    Microsoft Defender
    Other Info
    Logitech Z625 speaker system,
    Logitech BRIO 4K Pro webcam,
    HP Color LaserJet Pro MFP M477fdn,
    CyberPower CP1500PFCLCD
    Galaxy S23 Plus phone
  • Operating System
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    Surface Laptop 7 Copilot+ PC
    CPU
    Snapdragon X Elite (12 core) 3.42 GHz
    Memory
    16 GB LPDDR5x-7467 MHz
    Monitor(s) Displays
    15" HDR
    Screen Resolution
    2496 x 1664
    Hard Drives
    1 TB SSD
    Internet Speed
    Wi-Fi 7 and Bluetooth 5.4
    Browser
    Chrome and Edge
    Antivirus
    Microsoft Defender

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