Windows 11 25H2 & 26H2 Update Script 🚀✨

Enablement-package upgrades for Windows 11: 24H2 → 25H2 (KB5054156) and 24H2/25H2 → 26H2 (KB5121794) — one small package, one restart

This repository ships two enablement-package upgrade paths. 25H2 (1.0.0) upgrades 24H2 to 25H2 with KB5054156. 26H2 (1.1.0) upgrades 24H2 or 25H2 straight to 26H2 with KB5121794. Both come as a full PowerShell implementation and a reduced cmd.exe alternative, detect the architecture (including the ARM 64-bit Processor case), validate the package with SHA-1 and Authenticode, and keep transcripts. The 26H2 pair additionally refuses LTSC and server editions, supports a true read-only -WhatIf, and ships 57 Pester tests. The 25H2 scripts are unchanged.

⚡ Quick Start

PowerShell Version (Recommended)

# Clone and install
git clone https://github.com/paulmann/Windows-11-25H2-Update-Script.git
cd Windows-11-25H2-Update-Script

# Run as Administrator
.\Upgrade-Win11-To-25H2.ps1

# With custom parameters
.\Upgrade-Win11-To-25H2.ps1 -ForceReboot -RetryCount 5

# One-time bypass execution policy
powershell.exe -ExecutionPolicy Bypass -File ".\Upgrade-Win11-To-25H2.ps1"

Batch Version (Alternative)

# Download and run (Administrator required)
curl -L -o Upgrade-Win11-To-25H2.bat "https://github.com/paulmann/Windows-11-25H2-Update-Script/raw/main/Upgrade-Win11-To-25H2.bat"
Upgrade-Win11-To-25H2.bat

# Or run from repository
git clone https://github.com/paulmann/Windows-11-25H2-Update-Script.git
cd Windows-11-25H2-Update-Script
Upgrade-Win11-To-25H2.bat

26H2: from 24H2 or 25H2 (New in 1.1.0)

# Read-only preflight: prints build, edition, architecture, package and target; writes nothing
.\Upgrade-Win11-To-26H2.ps1 -WhatIf

# Install and leave the single restart for the maintenance window
.\Upgrade-Win11-To-26H2.ps1 -Reboot None

REM Or the cmd.exe alternative
Upgrade-Win11-To-26H2.bat /whatif
Upgrade-Win11-To-26H2.bat

📋 Table of Contents

🚀 Why Windows 11 25H2?
- The Enablement Package Advantage
- Real-World Benefits
✨ Key Features
📋 Installation & Usage
🏗️ Advanced Features
🔗 DevOps Integration
🏢 Enterprise Usage
🔍 Troubleshooting
🆕 Windows 11 26H2 (KB5121794)
🤝 Contributing
📄 License
👨‍💻 Author & Support
🎯 Roadmap

🚀 Why Windows 11 25H2?

The Enablement Package Advantage

Windows 11 25H2 uses the enablement package (eKB) technology, making the upgrade process incredibly efficient:

# Traditional feature update: 3-5 GB download, 30+ minutes
# Enablement package: ~50 KB download, 1-2 minutes!

# Features are pre-staged in 24H2, just activated by eKB
Target Build: 26200.6718 (from 26100.5074+)
Package: KB5054156

Real-World Benefits

⚡ Lightning Fast: Upgrade completes in under 2 minutes with just a restart
📦 Minimal Download: Tiny enablement package vs. multi-GB traditional updates
🔄 Shared Servicing: Uses same servicing branch as 24H2 for compatibility
🛡️ Production Ready: Leverages Microsoft's proven eKB technology
📈 Extended Support: Fresh 24-36 month support lifecycle begins

✨ Key Features

🛡️ Enterprise-Grade Safety

Administrator Validation: Automatic privilege checking with clear error messages
Digital Signature Verification: Validates MSU package authenticity (PowerShell only)
System Compatibility: Comprehensive build version and architecture checks
Rollback Protection: Safe failure handling with detailed error reporting

🎯 Intelligent Processing

Architecture Detection: Automatic x64/ARM64 detection with fallback prompts
Version Checking: Smart detection of current build and upgrade requirements
Download Optimization: BITS service with HTTP fallback and retry logic
Installation Control: Silent installation with configurable reboot behavior

📊 Comprehensive Reporting

Detailed Logging: Full transcript logging for audit and troubleshooting
Progress Tracking: Real-time status updates with color-coded messages
Error Classification: Structured error handling with resolution suggestions
Exit Code Management: Standard exit codes for automated deployment

🔄 Multi-Format Support

PowerShell Version: Full-featured with advanced error handling and logging
Batch Version: Simplified alternative that works without ExecutionPolicy changes
Cross-Platform: Both versions support x64 and ARM64 architectures
Deployment Ready: Perfect for Group Policy, SCCM, or manual execution

📋 Installation & Usage

System Requirements

Operating System: Windows 11, version 24H2 (Build 26100.5074 or later)
Architecture: x64 (AMD64) or ARM64
Privileges: Administrator rights required
Network: Internet connection for package download
PowerShell: Version 5.1+ (for PowerShell script)
Execution Policy: RemoteSigned or Unrestricted (for PowerShell script)

Installation Options

Option 1: Git Clone

# Clone repository
git clone https://github.com/paulmann/Windows-11-25H2-Update-Script.git
cd Windows-11-25H2-Update-Script

# Choose your preferred version:
# PowerShell: .\Upgrade-Win11-To-25H2.ps1
# Batch:      .\Upgrade-Win11-To-25H2.bat

Option 2: Direct Download

# PowerShell version
$url = 'https://github.com/paulmann/Windows-11-25H2-Update-Script/raw/main/Upgrade-Win11-To-25H2.ps1'
Invoke-WebRequest -Uri $url -OutFile 'Upgrade-Win11-To-25H2.ps1'

# Batch version
$url = 'https://github.com/paulmann/Windows-11-25H2-Update-Script/raw/main/Upgrade-Win11-To-25H2.bat'
Invoke-WebRequest -Uri $url -OutFile 'Upgrade-Win11-To-25H2.bat'

Option 3: Package Manager

# Using PowerShell Gallery (future)
# Install-Script -Name Windows11-25H2-Update

# Using Chocolatey (future)
# choco install windows11-25h2-update

PowerShell Setup

Administrator Privileges

This script MUST be run as Administrator. Right-click PowerShell and select Run as Administrator, or use:

# Start PowerShell as Administrator
powershell.exe -Command "Start-Process PowerShell -Verb RunAs"

Execution Policy

If you encounter "execution of scripts is disabled on this system":

# One-time bypass (recommended)
powershell.exe -ExecutionPolicy Bypass -File ".\Upgrade-Win11-To-25H2.ps1"

# Set for current user
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy RemoteSigned

# Temporary session policy
Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope Process

Batch File Setup

Administrator Privileges

The batch file MUST also run as Administrator:

# Right-click on batch file → "Run as administrator"
# Or from Administrator Command Prompt:
cd /d "C:\path\to\script"
Upgrade-Win11-To-25H2.bat

Advantages of Batch Version

✅ No ExecutionPolicy issues - works out of the box
✅ Simpler deployment - single .bat file
✅ Universal compatibility - works on any Windows system
✅ Group Policy friendly - easier to deploy via GPO
❌ No signature validation - less security verification
❌ Simpler error handling - basic error reporting

Usage Examples

PowerShell Usage

# Basic usage with default settings
.\Upgrade-Win11-To-25H2.ps1

# Force immediate reboot after installation
.\Upgrade-Win11-To-25H2.ps1 -ForceReboot

# Suppress reboot (manual reboot required later)
.\Upgrade-Win11-To-25H2.ps1 -NoRestart

# Custom retry settings for unstable networks
.\Upgrade-Win11-To-25H2.ps1 -RetryCount 10 -RetryDelaySec 30

# One-time execution with bypass
powershell.exe -ExecutionPolicy Bypass -File ".\Upgrade-Win11-To-25H2.ps1" -ForceReboot

Batch Usage

REM Basic usage
Upgrade-Win11-To-25H2.bat

REM The batch version automatically handles:
REM - Architecture detection
REM - Download with retry logic  
REM - Installation with progress display
REM - Reboot prompting

Parameters Comparison

Feature	PowerShell Version	Batch Version
Reboot Control	`-Reboot`, `-ForceReboot`, `-NoRestart`	Interactive prompt
Retry Logic	`-RetryCount`, `-RetryDelaySec`	Fixed (3 attempts, 5s delay)
Logging	Full transcript logging	Console output only
Signature Check	Yes (Get-AuthenticodeSignature)	No
Error Handling	Detailed with recommendations	Basic with codes
ExecutionPolicy	Required setup	Not applicable

🏗️ Advanced Features

Architecture Detection

Both scripts automatically detect your system architecture:

# Automatic detection logic
if ($env:PROCESSOR_ARCHITECTURE -eq "AMD64") {
    $downloadUrl = $x64Url
} elseif ($env:PROCESSOR_ARCHITECTURE -eq "ARM64") {
    $downloadUrl = $arm64Url
} else {
    # Fallback to user prompt (PowerShell only)
    Write-Host "Unable to detect architecture automatically"
    $choice = Read-Host "Specify architecture (AMD64/ARM64) [Default: AMD64]"
}

Supported URLs:

x64: KB5054156 for AMD64 architecture
ARM64: KB5054156 for ARM64 architecture (Surface Pro X, etc.)

Digital Signature Validation

PowerShell version includes comprehensive signature validation:

# Signature validation process
$signature = Get-AuthenticodeSignature -FilePath $msuFile

# Verify signature status
if ($signature.Status -ne 'Valid') {
    throw "Invalid signature status: $($signature.Status)"
}

# Verify Microsoft as signer
if ($signature.SignerCertificate.Subject -notmatch 'Microsoft Corporation') {
    throw "Untrusted signer: $($signature.SignerCertificate.Subject)"
}

Retry Logic

Robust download handling with configurable retry:

# PowerShell retry logic
for ($attempt = 1; $attempt -le $RetryCount; $attempt++) {
    try {
        # Try BITS first, fallback to HTTP
        if (Get-Service -Name BITS -ErrorAction SilentlyContinue) {
            Start-BitsTransfer -Source $Uri -Destination $OutFile
        } else {
            Invoke-WebRequest -Uri $Uri -OutFile $OutFile -UseBasicParsing
        }
        break
    }
    catch {
        if ($attempt -lt $RetryCount) {
            Start-Sleep -Seconds $RetryDelaySec
        } else {
            throw "Failed after $RetryCount attempts"
        }
    }
}

Logging System

PowerShell Logging:

# Comprehensive logging location
$logPath = "C:\ProgramData\Win11-25H2\Upgrade_20251001_142530.log"

# Log levels: Info, Warning, Error, Success
Write-Log "Starting Windows 11 25H2 upgrade process" -Level Info
Write-Log "Administrator privileges confirmed" -Level Success
Write-Log "Retrying download in 5 seconds..." -Level Warning
Write-Log "Installation failed with exit code 2359302" -Level Error

Batch Logging:

REM Basic console output with timestamps
echo [2025-10-01 14:25:30] [INFO] Starting update process
echo [2025-10-01 14:25:31] [SUCCESS] Administrator privileges confirmed
echo [2025-10-01 14:25:45] [WARNING] Download failed, retrying...
echo [2025-10-01 14:26:15] [SUCCESS] Installation completed successfully

🔗 DevOps Integration

CI/CD Pipeline Integration

GitHub Actions

name: Deploy Windows 11 25H2 Update
on:
  schedule:
    - cron: '0 2 * * 1' # Weekly on Monday 2 AM
  workflow_dispatch:

jobs:
  deploy-update:
    runs-on: self-hosted
    steps:
      - uses: actions/checkout@v3
      
      - name: Deploy PowerShell Version
        run: |
          powershell.exe -ExecutionPolicy Bypass -File ".\Upgrade-Win11-To-25H2.ps1" -NoRestart
        shell: cmd
        
      - name: Deploy Batch Version (Alternative)
        run: |
          .\Upgrade-Win11-To-25H2.bat
        shell: cmd

Azure DevOps

trigger:
  branches:
    include:
    - main

pool:
  name: 'Windows-Agents'

steps:
- powershell: |
    .\Upgrade-Win11-To-25H2.ps1 -RetryCount 5 -RetryDelaySec 10
  displayName: 'Upgrade to Windows 11 25H2'
  
- script: |
    if errorlevel 3010 (
        echo Reboot required - scheduling maintenance window
    )
  displayName: 'Handle Reboot Requirements'

Group Policy Deployment

Create a Group Policy Object (GPO) for mass deployment:

# PowerShell script deployment via GPO
# Computer Configuration → Policies → Windows Settings → Scripts (Startup/Shutdown)
# Add: powershell.exe -ExecutionPolicy Bypass -File "\\domain\sysvol\scripts\Upgrade-Win11-To-25H2.ps1"

# Batch file deployment via GPO (simpler)
# Computer Configuration → Policies → Windows Settings → Scripts (Startup/Shutdown)  
# Add: \\domain\sysvol\scripts\Upgrade-Win11-To-25H2.bat

SCCM Integration

Application Deployment:

REM Detection Method
reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CurrentBuild | find "26200"

REM Installation Command (PowerShell)
powershell.exe -ExecutionPolicy Bypass -WindowStyle Hidden -File ".\Upgrade-Win11-To-25H2.ps1" -NoRestart

REM Installation Command (Batch - Recommended for SCCM)
Upgrade-Win11-To-25H2.bat

REM Return Codes
REM 0 = Success
REM 3010 = Success, reboot required
REM 1 = Failure

🏢 Enterprise Usage

Mass Deployment

PowerShell DSC Configuration

Configuration Windows11_25H2_Update {
    Import-DscResource -ModuleName PSDesiredStateConfiguration
    
    Node "localhost" {
        Script UpdateWindows11 {
            SetScript = {
                & "C:\Scripts\Upgrade-Win11-To-25H2.ps1" -NoRestart
            }
            TestScript = {
                $build = (Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion").CurrentBuild
                return [int]$build -ge 26200
            }
            GetScript = {
                return @{ Result = "Windows 11 25H2 Update Status" }
            }
        }
    }
}

Intune Deployment (Win32 App)

# Package the batch file for Intune deployment
# Create intunewin file with Microsoft Win32 Content Prep Tool

# Install command
cmd /c "Upgrade-Win11-To-25H2.bat"

# Detection rule
if ((Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion").CurrentBuild -ge 26200) {
    Write-Output "Installed"
    exit 0
} else {
    exit 1
}

# Return codes
# 0 = Success
# 3010 = Success (reboot required)  
# Other = Failure

Automated Workflows

Task Scheduler Integration

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2">
  <Triggers>
    <CalendarTrigger>
      <StartBoundary>2025-10-01T02:00:00</StartBoundary>
      <ScheduleByWeek>
        <WeeksInterval>1</WeeksInterval>
        <DaysOfWeek>
          <Monday />
        </DaysOfWeek>
      </ScheduleByWeek>
    </CalendarTrigger>
  </Triggers>
  <Actions>
    <Exec>
      <Command>C:\Scripts\Upgrade-Win11-To-25H2.bat</Command>
    </Exec>
  </Actions>
  <Principals>
    <Principal>
      <UserId>S-1-5-18</UserId> <!-- SYSTEM account -->
      <RunLevel>HighestAvailable</RunLevel>
    </Principal>
  </Principals>
</Task>

Monitoring and Reporting

Event Log Integration

# PowerShell version writes to Application log
Write-EventLog -LogName Application -Source "Windows11Update" -EventId 1000 -Message "Upgrade started"

# Check upgrade status across domain
Get-ADComputer -Filter * | ForEach-Object {
    $build = Invoke-Command -ComputerName $_.Name -ScriptBlock {
        (Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion").CurrentBuild
    } -ErrorAction SilentlyContinue
    
    [PSCustomObject]@{
        ComputerName = $_.Name
        CurrentBuild = $build
        Is25H2 = [int]$build -ge 26200
    }
} | Export-Csv "Windows11_25H2_Status.csv"

🔍 Troubleshooting

Common Issues

Permission Errors

REM Problem: "Access denied" or "Administrator privileges required"
REM Solution: Always run as Administrator

REM Check current privileges
net session >nul 2>&1
if %errorlevel% neq 0 (
    echo ERROR: Administrator privileges required
    echo Right-click and select "Run as administrator"
    pause
    exit /b 1
)

ExecutionPolicy Issues (PowerShell Only)

# Problem: "cannot be loaded because running scripts is disabled"
# Solution: Use one-time bypass or adjust policy

# Quick fix - one-time bypass
powershell.exe -ExecutionPolicy Bypass -File ".\Upgrade-Win11-To-25H2.ps1"

# Permanent fix for current user
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy RemoteSigned

# Check current policy
Get-ExecutionPolicy -List

Download Failures

# Problem: Network issues, proxy, or firewall blocking
# Solutions:

# 1. Check internet connectivity
Test-NetConnection -ComputerName catalog.sf.dl.delivery.mp.microsoft.com -Port 443

# 2. Configure proxy (if needed)
netsh winhttp set proxy proxy-server:8080

# 3. Temporarily disable antivirus/firewall
# 4. Use batch version (simpler HTTP handling)

System Compatibility

# Problem: "Unsupported Windows version" 
# Check current build
$build = (Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion")
Write-Host "Current Build: $($build.CurrentBuild).$($build.UBR)"

# Requirements:
# Minimum: 26100.5074 (Windows 11 24H2)
# Target: 26200.6718 (Windows 11 25H2)

# Solution: Update to 24H2 first via Windows Update

Error Codes

Exit Code	PowerShell	Batch	Description	Solution
0	✅ Success	✅ Success	Installation completed	No action needed
3010	✅ Success, reboot required	✅ Success, reboot required	Installation successful	Reboot system
1	❌ General failure	❌ General failure	Various errors	Check logs
2359302	❌ Update not applicable	❌ Update not applicable	Already installed or incompatible	Verify system version
2359303	❌ Installation in progress	❌ Installation in progress	Another update running	Wait and retry
2147943458	❌ Access denied	❌ Access denied	Insufficient privileges	Run as Administrator

Diagnostic Commands

# System Information
winver                          # GUI version info
systeminfo | find "OS Version"  # Command line version info
Get-ComputerInfo | Select WindowsVersion, WindowsEditionId

# Registry Check
reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CurrentBuild
reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v UBR

# Architecture Check  
echo %PROCESSOR_ARCHITECTURE%   # CMD
$env:PROCESSOR_ARCHITECTURE     # PowerShell

# Download Test
ping catalog.sf.dl.delivery.mp.microsoft.com
nslookup catalog.sf.dl.delivery.mp.microsoft.com

# Service Status
sc query BITS                   # BITS service status
sc query wuauserv              # Windows Update service

🆕 Windows 11 26H2 (KB5121794)

Added in 1.1.0. Windows 11 24H2, 25H2 and 26H2 share one core operating system and the same monthly updates, so the enablement-package mechanism works one version further: KB5121794 is a ~174 KB "master switch" that turns 26H2 on with a single restart.

Which Script Do I Need?

Host	Script	Package	Result
24H2 → 25H2	`Upgrade-Win11-To-25H2.ps1` / `.bat`	KB5054156	26200.x
24H2 → 26H2	`Upgrade-Win11-To-26H2.ps1` / `.bat`	KB5121794	26300.x
25H2 → 26H2	`Upgrade-Win11-To-26H2.ps1` / `.bat`	KB5121794	26300.x
already 26H2 (26300.x)	either 26H2 script	—	"already at target", exit 0
26H1 (28000+) / LTSC / Server	none	—	refused: not an in-place path or not in the Applies To list

24H2 can go straight to 26H2; there is no need to pass through 25H2 first.

Requirements and Gates (26H2)

Gate	Rule
Version	24H2 build 26100.9546+ or 25H2 build 26200.9550+ (KB5124010 or later)
Edition	Home, Pro, Enterprise, Education, Enterprise multi-session, IoT Enterprise — not LTSC, not Windows Server
Architecture	AMD64 or ARM64; ARM is matched first, so `ARM 64-bit Processor` is not mistaken for x64
Target	any 26300.x is 26H2; build 28000+ (26H1) is refused before anything else
Package	pinned Microsoft delivery-CDN URL; SHA-1 fingerprint from the file name plus Authenticode signature; 100,000-byte sanity floor

There is no execution-policy gate: a policy that would block the script prevents it from starting, and the effective policy is logged for diagnostics.

Usage (26H2)

# Read-only preflight: no directory, no transcript, no download
.\Upgrade-Win11-To-26H2.ps1 -WhatIf

# Install and defer the restart to the maintenance window
.\Upgrade-Win11-To-26H2.ps1 -Reboot None

# Interactive restart after a successful install (default)
.\Upgrade-Win11-To-26H2.ps1

# Force a restart, or tune the download retries
.\Upgrade-Win11-To-26H2.ps1 -Reboot Force
.\Upgrade-Win11-To-26H2.ps1 -RetryCount 5 -RetryDelaySec 15

# Unknown architecture string, or unattended -WhatIf on such a host
.\Upgrade-Win11-To-26H2.ps1 -Architecture ARM64 -WhatIf

# Air-gapped host: local package; the file name must carry KB5121794 and the right architecture
.\Upgrade-Win11-To-26H2.ps1 -PackagePath C:\Packages\Windows11.0-KB5121794-x64_5e20a3cce48d6611b16bdec42b07167f5456586a.msu

Batch alternative (elevated Command Prompt): Upgrade-Win11-To-26H2.bat [/whatif]. It applies the same gates, retries 3 times 5 seconds apart, tries curl.exe and then pwsh/powershell inside each attempt, checks the SHA-1 with certutil, and always asks before restarting. It does not check Authenticode and keeps no transcript, so the PowerShell version is the safer choice.

Parameters (26H2)

Parameter	Values	Default	Effect
`-Reboot`	`Prompt`, `Force`, `None`	`Prompt`	reboot behaviour after a successful install
`-RetryCount`	1-10	3	download attempts; each tries BITS (if present) then HTTP
`-RetryDelaySec`	1-60	5	seconds between attempts
`-Architecture`	`Auto`, `AMD64`, `ARM64`	`Auto`	force a package; needed for `-WhatIf` when detection fails
`-PackagePath`	path to an MSU	none	local package; name must carry `KB5121794` and match the architecture
`-WhatIf`	switch	off	read-only preflight: no files, no download, no install

Exit Codes Mean "Staged"

The 26H2 script exits 0 when the package was accepted and staged, or when there was nothing to do, and 1 on every failure. 3010 is folded into 0, and the build does not change until the restart: verify CurrentBuild = 26300 (and DisplayVersion = 26H2) after the restart before recording a host as upgraded. A deployment tool must not treat 0 alone as proof.

Tests

Invoke-Pester -Path .\tests -Output Detailed

57 Pester tests: unit checks of the gates, per-ladder floors, architecture resolution, package identity, package verification and exit-code mapping, plus fixture runs of the observable paths. The fixtures force their branch inside a copy of the script (target build 1, raised minimum, 26H1 override, faked edition) and assert the absence of download/install markers, so the suite is safe and meaningful on any Windows host. Windows-only; PowerShell 7 + Pester 5.1 or later.

Package Verification (26H2)

Architecture	Size (bytes)	SHA-1
x64 (AMD64)	177,535	`5e20a3cce48d6611b16bdec42b07167f5456586a`
ARM64	178,969	`77a76caf2d362bb293a4d18058388f2717365abe`

x64:   https://catalog.sf.dl.delivery.mp.microsoft.com/filestreamingservice/files/94520a88-858f-4832-a57d-7211f6d84a4e/public/Windows11.0-KB5121794-x64_5e20a3cce48d6611b16bdec42b07167f5456586a.msu
ARM64: https://catalog.sf.dl.delivery.mp.microsoft.com/filestreamingservice/files/9d8dc3d0-9cbf-4eb1-9411-722e3e6a19b3/public/Windows11.0-KB5121794-arm64_77a76caf2d362bb293a4d18058388f2717365abe.msu

Both were downloaded and verified on 2026-10-25: SHA-1 matches the fingerprint published in the file name and the Authenticode signature is Microsoft Corporation. The package is delivered through Windows Update and WSUS (product "Windows 11", classification "Upgrades") and is not offered in the Microsoft Update Catalog, which is why the URLs are pinned; if they ever stop working, use -PackagePath with a stored copy.

26H2 limits: no rollback or uninstall; the edition gate reads two registry values, so a renamed SKU can pass; the 26H2 script was executed only on PowerShell 7.6.6 (the file is accepted by the Windows PowerShell 5.1 parser); the install path was not executed during development — the decision paths, the download/verification chain and both package files were.

🤝 Contributing

We welcome contributions! Here's how to get involved:

Development Setup

# Fork and clone the repository
git clone https://github.com/yourusername/Windows-11-25H2-Update-Script.git
cd Windows-11-25H2-Update-Script

# Test both versions
# PowerShell testing
powershell.exe -ExecutionPolicy Bypass -File ".\Upgrade-Win11-To-25H2.ps1" -WhatIf

# Batch testing in test environment
.\Upgrade-Win11-To-25H2.bat

Contribution Guidelines

Fork the repository
Create a feature branch (git checkout -b feature/awesome-feature)
Test thoroughly on multiple Windows 11 systems
Update documentation if needed
Commit changes (git commit -m 'Add awesome feature')
Push to branch (git push origin feature/awesome-feature)
Open a Pull Request

Code Standards

✅ PowerShell: Follow PowerShell best practices and PSScriptAnalyzer rules
✅ Batch: Use modern CMD syntax, proper error handling
✅ Documentation: Update README.md for new features
✅ Testing: Test on both x64 and ARM64 if possible
✅ Compatibility: Maintain Windows 11 24H2+ compatibility

Areas for Contribution

Proxy Support: Enhanced network configuration handling
Localization: Multi-language support for error messages
GUI Version: Windows Forms or WPF interface
Reporting: HTML/JSON output formats
Integration: Additional deployment methods (Chocolatey, winget)

📄 License

This project is licensed under the PolyForm Noncommercial License 1.0.0 - see the LICENSE file for details.

👨‍💻 Author & Support

Mikhail Deynekin

🌐 Website: deynekin.com
📧 Email: mid1977@gmail.com
🐙 GitHub: @paulmann

Getting Help

📖 Documentation: Read this README thoroughly
🐛 Bug Reports: Open an issue
💡 Feature Requests: Request features
💬 Questions: Check Discussions

Related Projects

Microsoft-Activation-Scripts - Windows activation tools
Windows11Debloat - Remove Windows 11 bloatware
PowerShell-Suite - PowerShell utilities collection

🎯 Roadmap

Upcoming Features

GUI Version: User-friendly Windows Forms interface
Package Managers: Chocolatey and winget support
Proxy Support: Enhanced corporate network compatibility
Scheduling: Built-in task scheduler integration
Rollback: Automated rollback capabilities
Multi-Language: Localized error messages and UI

Version History

v1.1.0 (2026-10-25):
- ✅ Added Windows 11 26H2 support (enablement package KB5121794) for 24H2 and 25H2 hosts: Upgrade-Win11-To-26H2.ps1 and Upgrade-Win11-To-26H2.bat
- ✅ Edition gate (LTSC editions and Windows Server refused), per-ladder prerequisite floor (24H2 26100.9546, 25H2 26200.9550), 26H1 refusal
- ✅ Real -WhatIf preflight (writes nothing, refuses instead of prompting), staged-vs-verified exit-code contract
- ✅ Local package identity check (KB5121794 + architecture), BITS job cleanup, batch download fallback inside each attempt
- ✅ 57 Pester tests, safe on any host, covering every gate and the package verification
v1.0.0 (2025-10-01):
- ✅ Initial PowerShell version with full feature set
- ✅ Added Batch file alternative for ExecutionPolicy-free deployment
- ✅ Comprehensive documentation and examples
- ✅ Enterprise deployment guides
- ✅ CI/CD integration examples

Feature Comparison Roadmap

Feature	Current Status	PowerShell	Batch	GUI (Planned)
Architecture Detection	✅ Complete	✅	✅	✅
Download with Retry	✅ Complete	✅	✅	✅
Digital Signature Check	⚠️ PS Only	✅	❌	✅
Comprehensive Logging	⚠️ PS Only	✅	⚠️	✅
Parameter Support	⚠️ PS Only	✅	❌	✅
Progress Reporting	🚧 Basic	⚠️	⚠️	✅
26H2 (KB5121794)	✅ Complete	✅	✅	✅
Rollback Support	❌ Planned	🚧	🚧	🚧
Proxy Support	❌ Planned	🚧	🚧	🚧

Legend: ✅ Complete | ⚠️ Partial | 🚧 In Progress | ❌ Not Available

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Windows 11 25H2 Update Script - Making Windows updates fast, reliable, and enterprise-ready 🚀✨

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Name		Name	Last commit message	Last commit date
tests		tests
.gitattributes		.gitattributes
AGENTS.md		AGENTS.md
LICENSE		LICENSE
README.md		README.md
Upgrade-Win11-To-25H2.bat		Upgrade-Win11-To-25H2.bat
Upgrade-Win11-To-25H2.ps1		Upgrade-Win11-To-25H2.ps1
Upgrade-Win11-To-26H2.bat		Upgrade-Win11-To-26H2.bat
Upgrade-Win11-To-26H2.ps1		Upgrade-Win11-To-26H2.ps1

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Windows 11 25H2 & 26H2 Update Script 🚀✨

⚡ Quick Start

PowerShell Version (Recommended)

Batch Version (Alternative)

26H2: from 24H2 or 25H2 (New in 1.1.0)

📋 Table of Contents

🚀 Why Windows 11 25H2?

The Enablement Package Advantage

Real-World Benefits

✨ Key Features

🛡️ Enterprise-Grade Safety

🎯 Intelligent Processing

📊 Comprehensive Reporting

🔄 Multi-Format Support

📋 Installation & Usage

System Requirements

Installation Options

Option 1: Git Clone

Option 2: Direct Download

Option 3: Package Manager

PowerShell Setup

Administrator Privileges

Execution Policy

Batch File Setup

Administrator Privileges

Advantages of Batch Version

Usage Examples

PowerShell Usage

Batch Usage

Parameters Comparison

🏗️ Advanced Features

Architecture Detection

Digital Signature Validation

Retry Logic

Logging System

🔗 DevOps Integration

CI/CD Pipeline Integration

GitHub Actions

Azure DevOps

Group Policy Deployment

SCCM Integration

🏢 Enterprise Usage

Mass Deployment

PowerShell DSC Configuration

Intune Deployment (Win32 App)

Automated Workflows

Task Scheduler Integration

Monitoring and Reporting

Event Log Integration

🔍 Troubleshooting

Common Issues

Permission Errors

ExecutionPolicy Issues (PowerShell Only)

Download Failures

System Compatibility

Error Codes

Diagnostic Commands

🆕 Windows 11 26H2 (KB5121794)

Which Script Do I Need?

Requirements and Gates (26H2)

Usage (26H2)

Parameters (26H2)

Exit Codes Mean "Staged"

Tests

Package Verification (26H2)

🤝 Contributing

Development Setup

Contribution Guidelines

Code Standards

Areas for Contribution

📄 License

👨‍💻 Author & Support

Getting Help

Related Projects

🎯 Roadmap

Upcoming Features