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AppxBackup PowerShell Module v2.1.0

Windows Application Package Backup & Restoration Toolkit

Version: 2.1.0
Release Date: July 27, 2026
PowerShell: 7.4+ (PowerShell Core only)

Table of Contents

Overview

AppxBackup is a complete 2026 rewrite of the 2016 original APPX backup script, transformed into a production-grade PowerShell module. This toolkit provides end-to-end Windows Store/MSIX application backup and restoration.

Key Capabilities

Complete Backup-to-Installation Pipeline - One-command backup, one-command restore
Automatic Certificate Management - Self-signed cert creation and system trust
Native Windows SDK Integration - MakeAppx and SignTool automation with tool-specific optimization
Modern MSIX Support - Full support for MSIX + legacy APPX formats
Externalized Configuration - Configuration values in JSON for easy customization

System Requirements

Minimum Requirements

  • PowerShell: 7.4
  • OS: Windows 10 1809 / Windows Server 2019
  • Windows SDK: 10.0.18362.0 (includes MakeAppx, SignTool)
  • Disk Space: 100 MB temporary storage
  • Memory: 512 MB available RAM

Recommended Configuration

  • PowerShell: 7.5+
  • OS: Windows 11 24H2 / Windows Server 2022
  • Windows SDK: 10.0.26100.0+ (includes MakeAppx, SignTool)
  • Disk Space: 1 GB+ for large packages
  • Memory: 2 GB+ available RAM

Administrator Privileges

Required for:

  • Installing certificates to LocalMachine store
  • Accessing WindowsApps folder on some systems

Not required for:

  • Basic backup operations (CurrentUser cert store)
  • Package creation
  • Most module functions

Installation

Quick Start (Developer Mode)

# 1. Clone or extract the module
cd "C:\Path\To\AppxBackup.Module"

# 2. Import the module
.\Import-AppxBackup.ps1

# 3. Verify installation
Get-Command -Module AppxBackup

Production Installation

# Install to PowerShell Modules directory
$modulePath = "$env:USERPROFILE\Documents\PowerShell\Modules\AppxBackup"
Copy-Item -Path ".\AppxBackup.Module" -Destination $modulePath -Recurse -Force

# Import globally
Import-Module AppxBackup -Force

# Verify
Get-Module AppxBackup

Workflow Example

For more detailed workflow examples, see Common Workflows in Examples/UsageExamples.md.

Scenario: Backup and Restore WorkMate App

Step 1: Backup the Application

# Find the installed app
$app = Get-AppxPackage -Name "*WorkMate*"

# Create complete backup (package + certificate)
Backup-AppxPackage -PackagePath $app.InstallLocation -OutputPath "D:\Backups"

Output:

=== Backup-AppxPackage v2.0 ===
Package: 2242AppsTeam.WorkMate v7.5.4.0

[Stage 1/6] Validating inputs...                         ✓
[Stage 2/6] Creating package...                          ✓ (6.4s, 47.95 MB)
[Stage 3/6] Creating certificate...                      ✓
[Stage 4/6] Installing certificate to Trusted Root...    ✓
[Stage 5/6] Signing package...                           ✓

✓ Certificate installed successfully - package is ready to install

To install the package, run:
  Install-AppxBackup -PackagePath 'D:\Backups\WorkMate_7.5.4.0_x64.appx'

Files Created:

D:\Backups\
├── 2242AppsTeam.WorkMate_7.5.4.0_x64__v313ts49xh8we.appx  (47.95 MB, signed)
└── 2242AppsTeam.WorkMate_7.5.4.0_x64__v313ts49xh8we.cer  (certificate)

Step 2: Install on Another Machine

# Single command - auto-detects certificate
Install-AppxBackup -PackagePath "D:\Backups\WorkMate_7.5.4.0_x64.appx"

Output:

=== APPX Package Installation Script ===

[1/3] Package Analysis
  Package: WorkMate_7.5.4.0_x64.appx
  Certificate: Auto-detected (WorkMate_7.5.4.0_x64.cer)

[2/3] Certificate Installation
  Target Store: Cert:\LocalMachine\Root
  Status: Installed successfully
  Thumbprint: 439F89C615A7468BF196D8951BBA4640C10D7D3F

[3/3] Package Installation
  Installing package...
  Status: Installed successfully
  Name: 2242AppsTeam.WorkMate
  Version: 7.5.4.0

=== Installation Complete ===

Available Commands

Public Functions

Function Description
Backup-AppxPackage Complete backup with cert creation and signing
Install-AppxBackup Installation with auto-cert handling and dependency orchestration
New-AppxBackupCertificate Create self-signed certificates (4096-bit RSA)
Get-AppxBackupInfo Analyze backup packages without installing
Export-AppxDependencies Extract and document package dependencies
Test-AppxPackageIntegrity Validate package structure and signatures
Test-AppxBackupCompatibility Check system compatibility before restore
Get-AppxToolPath Locate Windows SDK tools (MakeAppx, SignTool)

Private Functions (Internal)

  • Get-AppxConfiguration - Configuration loader from JSON files
  • Get-AppxDefault - Configuration value accessor with hierarchical fallback
  • Invoke-ProcessSafely - Robust external process execution with timeout
  • Get-AppxManifestData - XML manifest parsing with namespace handling
  • New-AppxPackageInternal - Core packaging logic with multi-tier fallback
  • Test-AppxToolAvailability - SDK tool validation and caching
  • Resolve-AppxDependencies - Recursive dependency graph analysis
  • ConvertTo-SecureFilePath - Path validation and sanitization
  • Write-AppxLog - Structured logging with level filtering
  • New-AppxBackupZipArchive - ZIP archive creation for dependency packages
  • New-AppxBackupManifest - Installation manifest generation
  • New-AppxDependencyCertificate - Dependency-specific certificate creation
  • ConvertTo-HtmlEncodedString - HTML entity encoding for safe output
  • Copy-AppxSourceDirectory - Robust directory copying with multi-tier fallback
  • Find-AppxSdkTool - Locate SDK tools in Program Files and registry
  • Get-AppxMakeAppxErrorAnalysis - Parse and interpret MakeAppx error messages
  • Install-AppxCertificateToStore - Install certificates to certificate stores
  • Invoke-AppxSignTool - SignTool wrapper with error handling
  • Remove-AppxItemWithRetry - Retry-based item removal with escalation
  • Resolve-AppxManifestNode - Resolve XML nodes with namespace fallback
  • Test-AppxArchitectureCompatibility - Check CPU architecture compatibility
  • Test-AppxDiskSpace - Validate available disk space
  • Test-AppxPackagingPrerequisites - Verify SDK tools and system requirements

Usage Examples

For the backup command: see Backup-AppxPackage in Examples/UsageExamples.md.

For the install command: see Install-AppxPackage in Examples/UsageExamples.md.

For more detailed usage examples, see the full Examples/UsageExamples.md.

Troubleshooting

Common Errors and Solutions

Error: 0x800B0109 (Certificate Not Trusted)

Cause: Certificate not in Trusted Root store
Solution:

# Run as Administrator
Import-Certificate -FilePath "path\to\cert.cer" `
    -CertStoreLocation "Cert:\LocalMachine\Root"

Error: 0x80073CF9 (Already Installed)

Cause: Package already installed
Solution:

Install-AppxBackup -PackagePath "package.appx" -Force

Error: MakeAppx Not Found

Cause: Windows SDK not installed
Solution:

  1. Install Windows SDK from Microsoft

Error: Access Denied (WindowsApps)

Cause: Insufficient permissions
Solution:

  • Module automatically uses multi-tier copy fallback
  • Robocopy → Copy-Item → .NET APIs
  • No manual intervention needed

Limitations

Restoration Behavior

Some applications cannot be successfully restored after being repackaged. If a repackaged application fails to install, the application cannot be used from the backup. Reinstall from the Microsoft Store.

Module Architecture

AppxBackup.Module/
├── AppxBackup.psd1           # Module manifest
├── AppxBackup.psm1           # Module loader
├── Test-AppxBackupModule.ps1 # Module test suite
├── Import-AppxBackup.ps1     # Quick import helper
│
├── Config/                   # Externalized configuration
│   ├── ModuleDefaults.json           # Core module constants
│   ├── ToolConfiguration.json        # Tool-specific settings
│   ├── WindowsReservedNames.json     # Reserved filenames
│   ├── PackageConfiguration.json     # Package-related constants
│   └── ZipPackagingConfiguration.json # ZIP archive settings
│
├── Public/                   # Exported functions
│   ├── Backup-AppxPackage.ps1          # Main backup function
│   ├── Install-AppxBackup.ps1          # Package installer (Restore-AppxPackage alias)
│   ├── New-AppxBackupCertificate.ps1   # Certificate creation
│   ├── Get-AppxBackupInfo.ps1          # Package analysis
│   ├── Export-AppxDependencies.ps1     # Dependency export
│   ├── Test-AppxPackageIntegrity.ps1   # Integrity validation
│   ├── Test-AppxBackupCompatibility.ps1 # Compatibility check
│   └── Get-AppxToolPath.ps1            # Tool locator
│
├── Private/                  # Internal functions
│   ├── Get-AppxConfiguration.ps1       # Configuration loader
│   ├── Get-AppxDefault.ps1             # Configuration value accessor
│   ├── Invoke-ProcessSafely.ps1        # Process execution
│   ├── Get-AppxManifestData.ps1        # Manifest parsing
│   ├── New-AppxPackageInternal.ps1     # Core packaging logic
│   ├── Test-AppxToolAvailability.ps1   # Tool validation
│   ├── Resolve-AppxDependencies.ps1    # Dependency resolution
│   ├── ConvertTo-SecureFilePath.ps1    # Path sanitization
│   ├── Write-AppxLog.ps1               # Logging system
│   ├── New-AppxBackupZipArchive.ps1    # ZIP archive creation
│   ├── New-AppxBackupManifest.ps1      # Installation manifest generation
│   ├── New-AppxDependencyCertificate.ps1 # Dependency certificate creation
│   ├── ConvertTo-HtmlEncodedString.ps1 # HTML encoding
│   ├── Copy-AppxSourceDirectory.ps1    # Directory copying
│   ├── Find-AppxSdkTool.ps1            # SDK tool locator
│   ├── Get-AppxMakeAppxErrorAnalysis.ps1 # MakeAppx error parser
│   ├── Install-AppxCertificateToStore.ps1 # Certificate installation
│   ├── Invoke-AppxSignTool.ps1         # SignTool wrapper
│   ├── Remove-AppxItemWithRetry.ps1    # Retry-based removal
│   ├── Resolve-AppxManifestNode.ps1    # XML node resolution
│   ├── Test-AppxArchitectureCompatibility.ps1 # Architecture check
│   ├── Test-AppxDiskSpace.ps1          # Disk space validation
│   └── Test-AppxPackagingPrerequisites.ps1 # Prerequisites check
│
└── Examples/                 # Usage examples
    └── UsageExamples.md

Testing Infrastructure

There are two complementary layers. The automated suite runs anywhere with no special privileges and gates every change; the interactive harness exercises real packaging against real installed applications and needs an administrator session.

Automated suite (build.ps1)

build.ps1 is the single entry point used by both contributors and CI, so a local pass and a CI pass mean the same thing.

# Everything: manifest and import check, static analysis, then the test suite
.\build.ps1

# Individual stages
.\build.ps1 -Task Build      # manifest validates, module imports, FileList matches disk
.\build.ps1 -Task Analyze    # PSScriptAnalyzer using PSScriptAnalyzerSettings.psd1
.\build.ps1 -Task Test       # Pester suite under tests/

# As CI runs it: NUnit + CSV artefacts under out/, and a meaningful exit code
.\build.ps1 -Task All -CI -FailOn Error

# Include the end-to-end packaging tests (requires the Windows SDK)
.\build.ps1 -Task Test -IncludeE2E

First run needs the tooling:

Install-Module Pester -MinimumVersion 5.5.0 -Scope CurrentUser -Force -SkipPublisherCheck
Install-Module PSScriptAnalyzer -MinimumVersion 1.21.0 -Scope CurrentUser -Force

The 73 tests in tests/ concentrate on the module's trust boundaries — path validation, external process execution, SDK discovery, configuration loading, and the agreement between the manifest, the loader and the files on disk. Each defect fixed in 2.1.0 has a regression test. The suite is written in the subset shared by Pester 5 and 6.

A second group of tests tagged E2E packages a synthetic source directory through the real Windows SDK MakeAppx — including a negative case asserting that a failed run surfaces the tool's own error text. These are excluded from the default run because they need the SDK; run them with .\build.ps1 -Task Test -IncludeE2E or Invoke-Pester -Path ./tests -TagFilter 'E2E'. They skip cleanly on machines without the SDK.

PSScriptAnalyzerSettings.psd1 is deliberately scoped to correctness rules, and every exclusion states why the rule does not apply here, so a finding is always worth acting on. CI blocks on errors and reports warnings without failing.

Recommended next steps

Known work that is tracked but not yet done:

  • Broaden the E2E coverage beyond New-AppxPackageInternal to Backup-AppxPackage and Install-AppxBackup. Those two additionally need a signing certificate and (for install) the Appx deployment service, which is not available on every host, so they will need their own tags and skip conditions.
  • PSScriptAnalyzer 1.25 raises an internal NullReferenceException while inspecting AppxBackup.psm1 through an absolute path. Analysis still completes with the full finding set, and build.ps1 reports the condition rather than failing on it. Revisit when a fixed analyzer version ships.

Test-AppxBackupModule.ps1

A comprehensive test harness that validates all 8 exported public functions with multiple parameter combinations.

Automatic app discovery via Get-AppxPackage pattern matching eliminates manual configuration. Full console transcript and structured results file saved to timestamped test run directories.

Usage:

# Test with custom app and output folder
.\Test-AppxBackupModule.ps1 -TestFolder "C:\Temp\AppxTest\" -AppName "Netflix"

# Include destructive installation test (optional)
.\Test-AppxBackupModule.ps1 -TestFolder "C:\Temp\" -AppName "Spotify" -TestInstall

Results include pass/fail/skip/error counts, detailed timing, and structured output suitable for CI/CD integration.

Configuration System

All hardcoded values are externalized to JSON configuration files in the Config/ directory:

  • ModuleDefaults.json - Path limits, timeouts, buffer sizes, disk space thresholds, etc.
  • ToolConfiguration.json - Tool-specific timeouts, async wait times, exit code interpretation
  • WindowsReservedNames.json - Windows reserved filenames for validation
  • PackageConfiguration.json - Package extensions, signature files, compression levels, namespaces
  • ZipPackagingConfiguration.json - ZIP archive structure, compression settings, manifest defaults, system requirements

Support

Getting Help

  • Documentation: Enter help Command (e. g. help Backup-AppxPackage)
  • Examples: See /Examples/UsageExamples.md
  • Issues: Check logs in $env:TEMP\AppxBackup_*.log

Reporting Issues

When reporting issues, include:

  1. PowerShell version ($PSVersionTable)
  2. Windows version (Get-ComputerInfo | Select OSName, OSVersion)
  3. Error message and stack trace
  4. Log file from $env:TEMP\AppxBackup_*.log

Changelog

Version 2.0.2 (February 13, 2026)

Code Quality & Maintainability

  • Extracted 11 new private helper functions to improve code organization and testability.
  • Refactored core functions (Backup-AppxPackage, New-AppxPackageInternal) by removing ~600 lines of duplicate/embedded logic.

Testing Infrastructure

  • New Test-AppxBackupModule.ps1 comprehensive test harness validates all 8 public functions with multiple parameter combinations.
  • Automatic app discovery, full transcript logging, and structured results with pass/fail/skip/error tracking for CI/CD integration.

Usage Examples & Documentation

  • Expanded Examples/UsageExamples.md with detailed examples for all public functions covering parameter usage and real-world scenarios.
  • Updated README with new Private Functions reference section documenting 11 helper functions and their purposes.

Disk Space & Package Validation

  • New Test-AppxDiskSpace() function validates disk space and warns about large packages (>1GB or >10k files by default).
  • Configurable size thresholds in PackageConfiguration for environment-specific requirements.

Directory Copying & File Operations

  • New Copy-AppxSourceDirectory() uses three-tier fallback strategy: Robocopy → Copy-Item → .NET APIs.
  • Handles WindowsApps folder permission issues transparently without user intervention.

System Requirements Validation

  • New Test-AppxPackagingPrerequisites() validates SDK tools and Windows version before packaging.
  • New Test-AppxArchitectureCompatibility() checks CPU architecture compatibility for installation.

Certificate & Signing Tools

  • New Install-AppxCertificateToStore() manages certificate installation to Windows certificate stores.
  • New Invoke-AppxSignTool() provides robust SignTool execution with error handling.

Diagnostic Improvements

  • New Get-AppxMakeAppxErrorAnalysis() parses MakeAppx error messages for better troubleshooting.
  • New Find-AppxSdkTool() locates SDK tools in Program Files and registry paths.

XML & Output Processing

  • New Resolve-AppxManifestNode() resolves XML nodes with namespace fallback strategies.
  • New ConvertTo-HtmlEncodedString() prevents XSS attacks in HTML dependency reports.

Installation & Cleanup

  • New Remove-AppxItemWithRetry() provides retry-based item removal with escalation for locked files.
  • Improved dependency resolution with metadata-driven installation orchestration.

Future Changes (Planned)

Nothing explicitly planned for future versions.

Citations

Author

Tchicdje Kouojip Joram Smith (DeltaGa)
Email: dev.github.tkjoramsmith@outlook.com
GitHub: https://github.com/DeltaGa

Original Repository

mjmeans/Appx-Backup: PowerShell script to backup an installed Windows Store App to an installable Appx file. (2016). GitHub.

© 2026 DeltaGa. All rights reserved.

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Windows Application Package Backup & Restoration Toolkit

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applicationapplication-backupappxbackupmicrosoft-storemicrosoft-store-appmsixwindowswindows-10windows-11windows-server-2019windows-storewindows-store-app

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