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Windows Server 2019 Windows Server 2019 Out-of-band update
Out-of-band

KB5059091

KB5059091: Cumulative update for Windows Server, version 2019, April 2025. Hyper-V-isolated Windows containers start reliably across update levels

In short

Fixes startup failures for some Windows containers running in Hyper-V isolation when their update level differs from the hosting utility virtual machine. It also includes a servicing stack update.

Does it affect you? Applies to: Devices running Windows Server 2019. The update package is for x64 systems.

Build
17763.7249
Restart
Required

Microsoft publishes separate notes for this KB for Windows 10.

What changes

Fix 1 change

Windows containers

For: Devices running Windows containers in Hyper-V isolation

  • Windows containers running in Hyper-V isolation can start when their update level differs from the hosting utility virtual machine.1
    Fixes startup failures caused by a mismatch between container and hosting utility virtual machine update levels, which could cause compatibility problems between system files.

Improvement 1 change

Servicing stack

  • The component that installs Windows updates receives quality improvements.2
    Includes servicing stack update KB5055662 (build 17763.7125).

Known issues

  1. Open Affects: Organizations and IT administrators

    Citrix

    Devices with Citrix Session Recording Agent version 2411 might fail to complete installation of the January 2025 Windows security update and roll back the changes. Home users are not expected to be affected.3

    How to apply the workaround Workaround

    Use Citrix Session Recording Agent version 2503 or newer; Citrix says these versions resolve the issue.3

Technical details

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

Data sheet

Released
2025-04-16
Classification
Updates
Type
Cumulative update
Restart
Required
Replaces
KB5058922, KB5050008, KB5037425
Replaced by
KB5058392
VersionBuildChannel
2019 17763.7249 General availability

Security

No vulnerabilities are listed for this update.

Downloads (Microsoft Update Catalog)

x64 2019
696.5 MB
windows10.0-kb5059091-x64.msu Main update · KB5059091 SHA-1: 60488c9d…03c92e

Updated components

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

Top changed componentsFiles
Networking3
Graphics and display2
Hyper-V and virtualization2
Kernel2
Secure Boot1
Security and sign-in1

Sources

Updated
Cited passages from Microsoft's official notes (3)
  1. 1. This update fixes an issue caused by 2025.04 B container images released on April 8, 2025 where Windows containers running in Hyper-V isolation mode could fail to start in some cases if their update level didn’t match that of the hosting utility virtual machine (UVM). support.microsoft.com
  2. 2. This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. support.microsoft.com
  3. 3. The issue has been resolved in Citrix Session Recording Agent version 2503, released on April 28, 2025, and newer versions. 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 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