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+---
+id: 'fb30b46a-ae2e-498f-b049-48f687fea928'
+slug: /fb30b46a-ae2e-498f-b049-48f687fea928
+title: 'Manage-WindowsInstallerCache'
+title_meta: 'Manage-WindowsInstallerCache'
+keywords: ['windows-installer', 'cache', 'msi', 'msp', 'quarantine', 'cleanup']
+description: 'Safely identifies and quarantines orphaned files in the Windows Installer cache to reclaim disk space.'
+tags: ['windows', 'disk-cleanup', 'installation', 'security']
+draft: false
+unlisted: false
+last_update:
+  date: 2026-06-08
+---
+
+## Description
+
+Identifies orphaned `.msi`, `.msp`, and `.mst` files in `C:\Windows\Installer` and safely quarantines them to reclaim disk space. The script validates files against the Windows Installer API, the `WindowsInstaller.Installer` COM object, and registry metadata before classifying anything as removable. The default mode is scan-only — no files are moved or deleted without explicit action.
+
+## Requirements
+
+- PowerShell 5.1 or newer
+- Local administrator rights
+- Access to `C:\Windows\Installer`
+
+## Usage
+
+Dry-run scan (default, no changes made):
+
+```powershell
+.\Manage-WindowsInstallerCache.ps1 -Verbose
+```
+
+Quarantine verified orphaned files:
+
+```powershell
+.\Manage-WindowsInstallerCache.ps1 -Quarantine -Verbose
+```
+
+Quarantine orphaned and unverified files without prompting:
+
+```powershell
+.\Manage-WindowsInstallerCache.ps1 -Quarantine -Force
+```
+
+Delete previously quarantined files:
+
+```powershell
+.\Manage-WindowsInstallerCache.ps1 -Delete -ManifestPath "C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache\Manage-WindowsInstallerCache-20260529-120001-manifest.json"
+```
+
+Restore quarantined files:
+
+```powershell
+.\Manage-WindowsInstallerCache.ps1 -Restore -RestoreFromManifest "C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache\Manage-WindowsInstallerCache-20260529-120001-manifest.json"
+```
+
+## File Classifications
+
+Each file in the installer cache receives one of the following classifications:
+
+| Classification | Meaning | Eligible for Quarantine |
+| --- | --- | --- |
+| `SAFE_ORPHAN` | No full-path or weak reference found; all validation sources enumerated cleanly. | Yes (default) |
+| `POSSIBLE_REFERENCE` | No full-path reference found, but filename-only evidence exists in one or more sources. | No |
+| `UNVERIFIED` | No reference found, but one or more validation layers failed to enumerate cleanly. | Only with `-Force` or operator confirmation |
+| `ACTIVE_REFERENCE` | File found in one or more full-path validation sources. | No |
+
+## Parameters
+
+| Parameter | Required | Default | Type | Description |
+| --- | --- | --- | --- | --- |
+| `ScanOnly` | No | Active when no mode switch is supplied | Switch | Performs discovery and classification only. |
+| `Quarantine` | No | `False` | Switch | Moves `SAFE_ORPHAN` files to the quarantine folder (`C:\Windows\Installer\_Quarantine` by default). |
+| `Delete` | No | `False` | Switch | Permanently deletes previously quarantined files referenced by a manifest. |
+| `Restore` | No | `False` | Switch | Restores previously quarantined files from a manifest back to their original location. |
+| `RestoreFromManifest` | No | Newest manifest in log path | String | Path to the manifest used for restore. |
+| `ManifestPath` | No | Newest manifest in log path | String | Path to the manifest produced by a `-Quarantine` run. Created automatically when at least one file is quarantined — records each file's original path, quarantine destination, hash, size, classification, and timestamp. Supply this path to `-Delete` or `-Restore`. |
+| `InstallerPath` | No | `C:\Windows\Installer` | String | Root installer cache path to inspect. |
+| `QuarantinePath` | No | `C:\Windows\Installer\_Quarantine` | String | Quarantine destination folder. |
+| `LogPath` | No | `C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache` | String | Folder for JSON, CSV, and manifest output. |
+| `Force` | No | `False` | Switch | Suppresses confirmation prompts for `UNVERIFIED` files during quarantine, quarantining them automatically. |
+
+## Output
+
+The script writes:
+
+- JSON audit log with findings, actions, validation errors, and manifest references
+- CSV audit log (suitable for ticket attachments or CAB evidence)
+- Scan report CSV with per-file classification details (scan and quarantine modes)
+- Rollback manifest (created when files are quarantined)
+
+Default output location:
+
+```text
+C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache\Manage-WindowsInstallerCache-<timestamp>.json
+C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache\Manage-WindowsInstallerCache-<timestamp>.csv
+C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache\Manage-WindowsInstallerCache-<timestamp>-manifest.json
+```
+
+## Sample Output
+
+```powershell
+PS C:\> .\Manage-WindowsInstallerCache.ps1 -Verbose
+
+InstallerPath        : C:\Windows\Installer
+QuarantinePath       : C:\Windows\Installer\_Quarantine
+TotalFiles           : 612
+SafeOrphans          : 4
+PossibleReferences   : 2
+Unverified           : 0
+ActiveReferences     : 606
+ValidationErrorCount : 0
+ManifestPath         :
+JsonLogPath          : C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache\Manage-WindowsInstallerCache-20260529-141500.json
+CsvLogPath           : C:\ProgramData\_Automation\Script\Manage-WindowsInstallerCache\Manage-WindowsInstallerCache-20260529-141500.csv
+```
+
+## Changelog
+
+### 2026-06-09
+
+- Updated documentation to reflect classification model and safety details
+
+### 2026-06-08
+
+- Initial version of the document