Description

The windows-latest GitHub Actions runner now resolves to windows-2025-vs2026 (image windows-2025-vs2026, version 20260608.135.2), which ships with Visual Studio 2026. This change was rolled out between June 8–15, 2026.

The action fails at the "Updating Windows environment..." step with:

##[error]Failed to find vcvarsall.bat

Root cause

The KNOWN_VISUAL_STUDIO_INSTALLATIONS array only includes paths for VS 2017, 2019, and 2022. The VS2026 installation path (C:\Program Files\Microsoft Visual Studio\18\Enterprise) is not listed, so findVcvarsallPath() fails.

Reproduction

Any workflow using windows-latest with this action:

jobs:
  build:
    runs-on: windows-latest
    steps:
      - uses: actions/checkout@v4
      - uses: graalvm/setup-graalvm@v1
        with:
          version: mandrel-latest
          java-version: '25'
          github-token: ${{ secrets.GITHUB_TOKEN }}

Example failing run: https://github.com/quarkus-qe/quarkus-test-suite/actions/runs/27516266920/job/81327476930

Suggested fix

Add the VS2026 path to KNOWN_VISUAL_STUDIO_INSTALLATIONS in src/msvc.ts:

'C:\\Program Files\\Microsoft Visual Studio\\18\\Enterprise'

Workaround

Pin the runner to windows-2022:

runs-on: windows-2022