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Release Date:
May 14, 2024

.NET Framework 3.5 and 4.8.1

The May 14, 2024 update for Microsoft server operating system, version 23H2 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.


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


- Addresses an issue where crashes can occur if several threads all concurrently query the ITypeInfo implementation of the same managed type.

- Addresses an issue with ISymUnmanagedReader::GetMethodsFromDocumentPosition and ISymUnmanagedReader2::GetMethodsInDocument API's might result in incorrect results under certain circumstances.

.NET Libraries

- Addresses an issue which can be triggered in the fbx file parser.

- Addresses an issue to use MIST validated implementations of FIPS algorithms.

.NET Fundamentals

- Addresses an issue with wildcard format changes introduced in IIS 10.


- Addresses an issue where apps crash when calling GetWindowText and GetWindowTextLength methods.

1Common Language Runtime (CLR)

2Windows 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 Channel


Next Step

Windows Update and Microsoft Update


None. This update will be downloaded and installed automatically from Windows Update.

Windows Update for Business


None. This update will be downloaded and installed automatically from Windows Update.

Microsoft Update Catalog


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

Windows Server Update Services (WSUS)


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

Product: Microsoft server operating system, version 23H2

Classification: Updates

File information

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 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.

How to obtain help and support for this update

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