Windows 11 users are experiencing a bug where Windows Sandbox hangs at the splash screen. The application stays on the logo for about 10 minutes, then fails with a timeout error. This issue affects Windows 11 version 25H2 (Build 2600.7462) and 26H1 (Build 28000 series).

You will see this error message:

This operating system returned because the timeout period expired

Why Error 0x800705b4 Occurs

Updates KB5070311 and KB5072033 interfere with the sandbox startup process. While the sandbox loads, the system generates large temporary files. These files can reach 2 GB and are stored in .

A subprocess, likely coreclr.dll, stops responding during this process. Since the sandbox takes too long to load, the system cancels the launch and returns code 0x800705b4. This bug is limited to the virtual environment. It does not impact your main Windows installation. For more help, see these Windows fixes to keep your PC stable.

Solution 1: Install Update KB5077239

Microsoft released a preview update that addresses the startup hang. This is the fastest way to resolve the error.

  1. Open Settings.
  2. Go to Windows Update.
  3. Check for updates and find KB5077239 (OS Build 28000.1643).
  4. Download and install it.
  5. Restart your computer.

Solution 2: Repair Windows Update via Recovery

If the update does not appear in your settings, use the recovery tool to refresh the sandbox files.

  1. Go to Settings > System > Recovery.
  2. Find Fix problems using Windows Update.
  3. Click Reinstall now.
  4. Check the box to Automatically restart my PC 15 minutes after installation.
  5. Click OK. This reinstall keeps your files and apps while fixing the underlying bug.

Solution 3: Reset the Windows Sandbox Feature

Turning the sandbox off and on again clears out stuck files in the ContainerStorages folder.

  1. Open Control Panel.
  2. Go to Programs > Programs and Features.
  3. Click Turn Windows features on or off.
  4. Find Windows Sandbox, uncheck it, and click OK.
  5. Restart your computer.
  6. Go back, check Windows Sandbox again, and restart one more time.

Solution 4: System File Maintenance

If the timeout persists, check your system files for errors. You can use PowerShell commands or the command prompt for these repairs.

  1. Open Terminal (Admin) or Command Prompt (Admin).
  2. Run this command:

Microsoft (R) Windows (R) Resource Checker Version 6.0

Copyright (C) Microsoft Corporation. All rights reserved.

Scans the integrity of all protected system files and replaces incorrect versions with

correct Microsoft versions.

SFC [/SCANNOW] [/VERIFYONLY] [/SCANFILE=] [/VERIFYFILE=]

[/OFFWINDIR=<offline windows directory> /OFFBOOTDIR=<offline boot directory> [/OFFLOGFILE=<log file path>]]

/SCANNOW Scans integrity of all protected system files and repairs files with

            problems when possible.

/VERIFYONLY Scans integrity of all protected system files. No repair operation is

            performed.

/SCANFILE Scans integrity of the referenced file, repairs file if problems are

            identified. Specify full path <file>

/VERIFYFILE Verifies the integrity of the file with full path . No repair

            operation is performed.

/OFFBOOTDIR For offline repair, specify the location of the offline boot directory

/OFFWINDIR For offline repair, specify the location of the offline windows directory

/OFFLOGFILE For offline repair, optionally enable logging by specifying a log file path

e.g.

    sfc /SCANNOW

    sfc /VERIFYFILE=c:windowssystem32kernel32.dll

    sfc /SCANFILE=d:windowssystem32kernel32.dll /OFFBOOTDIR=d: /OFFWINDIR=d:windows

    sfc /SCANFILE=d:windowssystem32kernel32.dll /OFFBOOTDIR=d: /OFFWINDIR=d:windows /OFFLOGFILE=c:log.txt

    sfc /VERIFYONLY
  1. When that finishes, run this command:
    4. Restart the computer and try to open the sandbox.

Need hands-on help? Contact our team.

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