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.NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 Update
Patch Tuesday

KB5056580

KB5056580: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows 11 23H2, July 2025. Type conversion and .NET load error dialogs addressed

In short

.NET type conversion concurrency and error dialogs from some library loads are addressed. The Windows 11 22H2 package is now available through WSUS and the Update Catalog.

Does it affect you? Applies to: Devices running Windows 11, version 22H2 or 23H2, with .NET Framework 3.5 or 4.8.1 installed.

File version
2.0.50727.9179 · 4.8.9310.0
Restart
Required

What changes

Improvements 2 changes

.NET Libraries

For: .NET app users

  • The update addresses a concurrency problem that can affect type conversion in .NET apps.1
    Addresses an issue involving TypeDescriptor.GetConverter() and TypeDescriptor.GetProperties().

.NET Runtime

For: .NET app users

  • The update addresses error dialogs that can appear when some .NET libraries load.2
    Addresses error reporting dialogs triggered by interactions between .NET Framework DLL loads and the OS code integrity enforcement policy.

Known issues

  1. Open Affects: Organizations and IT administrators

    The Windows 11, version 22H2 package KB5056580 was not available on Windows Server Update Services (WSUS) or Microsoft Update Catalog.

    The Windows 11, version 22H2 package was missing from WSUS and the Update Catalog. Microsoft published it there on July 14, 2025.3

    How to apply the workaround Workaround

    Before it was published there, the package could be installed through Windows Update or Microsoft Update.3

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2025-07-08
Classification
Updates
Type
Cumulative update
Restart
Required
Replaced by
KB5066133
VersionFile versionChannel
3.5 2.0.50727.9179 General availability
4.8.1 4.8.9310.0 General availability

Security

No vulnerabilities are listed for this update.

Updated components

70 files changed since the previous update for the same versions.

Top changed componentsFiles
WPF24
.NET runtime (CLR)12

Sources

Updated
Cited passages from Microsoft's official notes (3)
  1. 1. Addresses an issue with concurrency in TypeDescriptor.GetConverter()issue in TypeDescriptor GetProperties() and GetConverter(). support.microsoft.com
  2. 2. Addresses an issue where interactions between .NET Framework DLL loads and OS code integrity enforcement policy trigger error reporting dialog boxes. support.microsoft.com
  3. 3. The Windows 11, version 22H2 package KB5056580 was published on Windows Server Update Service (WSUS) and Microsoft Update Catalog on July 14th, 2025. support.microsoft.com
Checked automatically: 8 of 8 checks passed, 3 quoted passages · compared with Microsoft's page on Oct 20, 2026
  • Quotes found in the official pages: passed
  • Numbers found in the sources: passed
  • Vulnerabilities from the dossier only: passed
  • Links to allowed domains only: passed
  • Every official change covered: passed
  • Readable plain text: passed
  • Changes confirmed by the file list: passed
  • Sources agree: passed

A second AI read the text against the sources: correctness 5/5, clarity 4/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake