git-ecosystem/git-credential-manager · error · Trace2Exception

Failed to start Git helper

Error message

Failed to start Git helper '{0}'

What it means

Git.InvokeHelperAsync spawns a Git helper subprocess (e.g. git-credential-manager or another helper) with the given arguments. If ChildProcess.Start returns false — the OS could not launch the process — a Trace2Exception is thrown with the helper's argument list. This indicates the helper binary or its launcher could not be started at all.

Solutions

1. Verify the Git installation and that the helper binary named in the message exists and is executable at that path.
2. Reinstall or repair Git so helper executables are restored.
3. Check antivirus/EDR or AppLocker policies that may block spawning the helper process.
4. Confirm GitInstallation/Path configuration points at the intended Git distribution, then retry.

Example fix

// diagnosis: message shows which args failed
// before (broken install)
C:\Program Files\Git\mingw64\libexec\git-core\git-credential-manager.exe  // missing
// after
// reinstall Git so the helper exists, e.g. `winget install Git.Git`, then retry

if (!File.Exists(helperPath))
{
    throw new InvalidOperationException($"Git helper not found at '{helperPath}'. Reinstall Git.");
}

try
{
    var result = await git.InvokeHelperAsync(args, standardInput);
}
catch (Trace2Exception ex)
{
    logger.LogError(ex, "Could not start the Git helper process. Check the Git installation and that the helper path is executable.");
}

When it happens

Trigger: Calling InvokeHelperAsync (directly or via Config/Credential helper invocations) when the constructed ProcessStartInfo's executable cannot be started: the helper binary path is wrong, the file is missing, the platform cannot execute it, or process creation fails for permission/resource reasons.

Common situations: Broken or partial Git installation where git-credential-* helper binaries are missing; antivirus or policy blocking process spawn; wrong GitInstallation path after a Git upgrade; running the app in a sandbox without execute permission.

Related errors

• helper error ( )
• Cannot prompt because terminal prompts have been disabled.
• Missing 'protocol' request argument
• Invalid 'protocol' request argument (cannot be empty)
• Missing 'host' request argument

AI-assisted analysis of git-ecosystem/git-credential-manager@e8ce762cd0 (2026-09-11). Data as JSON: /api/errors/ef768e4a07b5fa75. Report an issue: GitHub.

Appendix: source

Thrown at src/Core/Git.cs:250

        // protocol will one day use a different IPC mechanism, whereas this code
        // has to follow what upstream Git does.
        public async Task<IDictionary<string, string>> InvokeHelperAsync(string args, IDictionary<string, string> standardInput = null)
        {
            var procStartInfo = new ProcessStartInfo(_gitPath)
            {
                Arguments = args,
                RedirectStandardInput = true,
                RedirectStandardOutput = true,
                RedirectStandardError = false, // Do not redirect stderr as tracing might be enabled
                UseShellExecute = false
            };

            var process = _processManager.CreateProcess(procStartInfo);
            if (!process.Start(Trace2ProcessClass.Git))
            {
                var format = "Failed to start Git helper '{0}'";
                var message = string.Format(format, args);
                throw new Trace2Exception(_trace2, message, format);
            }

            if (!(standardInput is null))
            {
                await process.StandardInput.WriteDictionaryAsync(standardInput);
                // some helpers won't continue until they see EOF
                // cf git-credential-cache
                process.StandardInput.Close();
            }

            IDictionary<string, string> resultDict = await process.StandardOutput.ReadDictionaryAsync(StringComparer.OrdinalIgnoreCase);

            await Task.Run(() => process.WaitForExit());
            int exitCode = process.ExitCode;

            if (exitCode != 0)
            {
                if (!resultDict.TryGetValue("error", out string errorMessage))

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