MahApps/MahApps.Metro · error · Exception

The GITHUB_TOKEN environment variable is not defined.

Error message

The GITHUB_TOKEN environment variable is not defined.

What it means

The Cake 'CreateRelease' task needs a GitHub access token to call GitReleaseManagerCreate and publish a release to the MahApps repo. It reads GITHUB_TOKEN from the environment and throws a plain Exception when the variable is empty or unset. The task is gated by !data.IsPullRequest, so it only runs on non-PR (push/release) builds.

Source

Thrown at build.cake:330

    .Description("Ensures XAML Formatting is Clean")
    .Does(() =>
{
    Func<IFileSystemInfo, bool> exclude_Dir =
        fileSystemInfo => !fileSystemInfo.Path.Segments.Contains("obj") && !fileSystemInfo.Path.ToString().Contains("Styles/Themes");

    var files = GetFiles(srcDir + "/**/*.xaml", new GlobberSettings { Predicate = exclude_Dir });
    Information("\nChecking " + files.Count() + " file(s) for XAML Structure");
    ExecuteProcess(styler, "-f \"" + string.Join(",", files.Select(f => f.ToString())) + "\" -c \"" + stylerFile + "\"");
});

Task("CreateRelease")
    .WithCriteria<BuildData>((context, data) => !data.IsPullRequest)
    .Does<BuildData>(data =>
{
    var token = EnvironmentVariable("GITHUB_TOKEN");
    if (string.IsNullOrEmpty(token))
    {
        throw new Exception("The GITHUB_TOKEN environment variable is not defined.");
    }

    GitReleaseManagerCreate(token, "MahApps", repoName, new GitReleaseManagerCreateSettings {
        Milestone         = data.GitVersion.MajorMinorPatch,
        Name              = data.GitVersion.AssemblySemFileVer,
        Prerelease        = data.IsPrerelease,
        TargetCommitish   = data.GitVersion.BranchName,
        WorkingDirectory  = "."
    });
});

///////////////////////////////////////////////////////////////////////////////
// HELPER
///////////////////////////////////////////////////////////////////////////////

void SignFiles(IEnumerable<FilePath> files, string description)
{
    var vurl = EnvironmentVariable("azure-key-vault-url");

View on GitHub (pinned to 72099e310b)

Solutions

1. Set the GITHUB_TOKEN environment variable before invoking Cake: in PowerShell use $env:GITHUB_TOKEN = '<token>'; in GitHub Actions use the automatic GITHUB_TOKEN secret (secrets.GITHUB_TOKEN) passed via env:.
2. Verify the CI job that runs CreateRelease actually has the secret in its environment (not just at workflow level).
3. If you are testing locally and don't need a release, run a different target (e.g. Default) instead of CreateRelease.
4. For GitHub Actions, map the built-in token explicitly: env: GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}.

Example fix

# before (PowerShell, token missing)
./build.ps1 -Target CreateRelease
# after
$env:GITHUB_TOKEN = '<your PAT or CI token>'
./build.ps1 -Target CreateRelease

# GitHub Actions
env:
  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

// Before CreateRelease, validate the token and fail with a clear message
var token = EnvironmentVariable("GITHUB_TOKEN");
if (string.IsNullOrEmpty(token)) {
    Warning("GITHUB_TOKEN not set — skipping CreateRelease.");
    return; // or: throw with remediation hint
}
GitReleaseManagerCreate(token, "MahApps", repoName, new GitReleaseManagerCreateSettings { /* ... */ });

When it happens

Trigger: The 'CreateRelease' target executes (local or CI, not a PR build) and EnvironmentVariable("GITHUB_TOKEN") returns null or empty. GitReleaseManagerCreate is never reached because the guard throws first.

Common situations: CI secret not configured (e.g. GITHUB_TOKEN missing from GitHub Actions secrets or AppVeyor environment). Running build.ps1 -Target CreateRelease locally without setting GITHUB_TOKEN in the shell. Token secret renamed or scoped away from the build job.

Related errors

• {repoName} will only build on Windows because it's not possi
• File not found: {fileName}
• Errors occurred:{Environment.NewLine} {string.Join(Environme
• Exit code: {exitCode}

AI-assisted analysis of MahApps/MahApps.Metro@72099e310b (2026-08-13). Data as JSON: /api/errors/73c3e897c5c18299. Report an issue: GitHub.