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Maester 3.0: a new test engine, and a heads-up for preview users

· 14 min read
Merill Fernando
Merill Fernando
Maester maintainer + Product Manager, Microsoft

Maester 3.0 merges into main on Thursday, 8 October 2026 at 10:00 UTC (8 pm AEST). From that moment the preview build of Maester on the PowerShell Gallery is Maester 3.0, and 3.0 has breaking changes.

If you run Maester in automation with the preview build, switch to the release build now

Your next scheduled run after the merge will pick up 3.0. The biggest change is that Maester 3.0 needs PowerShell 7.4 or later. Windows PowerShell 5.1 is no longer supported. We've worked hard to keep your custom tests (including Pester tests) working, but a rewrite this size will have rough edges.

You're on the preview build if your pipeline does any of these:

  • Install-Module Maester -AllowPrerelease or Update-Module Maester -AllowPrerelease
  • maester_version: preview in the Maester GitHub Action

To stay on 2.x, install the release build instead: drop -AllowPrerelease, or pin the version with Install-Module Maester -RequiredVersion 2.3.0. In the GitHub Action, use maester_version: latest.

NowMove automation off the preview build
8 Oct, 10:00 UTC3.0 merges into main and becomes the preview build
After thatWe fix what the preview finds, then ship 3.0 as the release build

If you're using Maester interactively and want to see what's coming, the preview is exactly where we want you. Try it, and tell us what breaks.