Windows Server 2019 — PowerShellGet install-module fails with repository policy is untrusted — Fix & Prevention

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution — Primary Fix
7. Solution — Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Install-Module on Windows Server 2019 prompts repeatedly or fails because the PSGallery is marked untrusted, breaking automation scripts.

Environment & Reproduction

Reproduces when a fresh server runs PSGallery installs in non-interactive mode and InstallationPolicy is still Untrusted.

Install-Module Az -Force

Root Cause Analysis

PowerShellGet treats PSGallery as untrusted by default, so silent installs error out unless the policy is updated or the cmdlet uses -Force.

Quick Triage

Inspect repository policy and PowerShellGet module version on the server.

Get-PSRepository
Get-Module PowerShellGet -ListAvailable

Step-by-Step Diagnosis

Re-run the module install with -Verbose to confirm the trust prompt is the blocker.

Install-Module Az -Verbose -ErrorAction Stop

Solution — Primary Fix

Trust the PSGallery repository for the machine and ensure PowerShellGet is up to date.

Set-PSRepository -Name PSGallery -InstallationPolicy Trusted
Install-Module PowerShellGet -Force -AllowClobber
Install-Module Az -Scope AllUsers -Force

Solution — Alternative Approaches

Register an internal NuGet feed and source modules from there to avoid trusting the public gallery.

Register-PSRepository -Name InternalPS -SourceLocation https://nuget.local/psgallery -InstallationPolicy Trusted

Verification & Acceptance Criteria

Modules install non-interactively and Get-InstalledModule returns expected versions.

Get-InstalledModule Az

Rollback Plan

Reset PSGallery to Untrusted if required by audit policy.

Set-PSRepository -Name PSGallery -InstallationPolicy Untrusted

Prevention & Hardening

Configure DSC or GPO to set repository trust uniformly across servers.

# DSC PSModule resource ensures repository policy

Related Errors & Cross-Refs

Related: NuGet provider missing, TLS 1.2 errors during module pull, and proxy authentication failures.

Related tutorial: View the step-by-step tutorial for Windows Server 2019.

View all Windows Server 2019 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Microsoft Learn documentation for PowerShellGet, repositories, and module trust policies.