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.NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 Optional preview
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KB5054979

KB5054979: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows 11 24H2 and Windows Server 2025, April 2025. UNC file and directory operations get a reliability fix

In short

Addresses an issue with .NET file and directory operations on UNC shares. It contains no new security improvements.

Does it affect you? Applies to: Devices running Windows 11, version 24H2, or Windows Server 2025 with .NET Framework 3.5 or 4.8.1 installed.

File version
2.0.50727.9179 · 4.8.9300.0
Restart
Required

What changes

Fix 1 change

.NET Fundamentals

  • Addresses an issue with file and directory operations on network shares.1
    The issue involves System.IO APIs operating on files and directories on UNC shares.

Technical details

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

Data sheet

Released
2025-04-08
Classification
Updates
Type
Cumulative update
Restart
Required
Replaces
KB5050577, KB5048162, KB5045934
Replaced by
KB5056579
VersionFile versionChannel
3.5 2.0.50727.9179 General availability
4.8.1 4.8.9300.0 General availability

Security

No vulnerabilities are listed for this update.

Downloads (Microsoft Update Catalog)

x64 Windows 11, version 24H2 / Windows Server 2025
71.6 MB
windows11.0-kb5054979-x64-ndp481.msu Main update · KB5054979 SHA-1: 8e2f730b…751c07
Arm64 Windows 11, version 24H2 / Windows Server 2025
88.1 MB
windows11.0-kb5054979-arm64-ndp481.msu Main update · KB5054979 SHA-1: 21676b5c…f9e460

Updated components

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

Top changed componentsFiles
.NET runtime (CLR)12

Sources

Updated
Cited passages from Microsoft's official notes (1)
  1. 1. Addresses an issue where System.IO APIs are used to operate on files and directories on UNC shares. support.microsoft.com
Checked automatically: 8 of 8 checks passed, 1 quoted passage · 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 5/5, 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