CoplayDev/unity-mcp · error · InvalidOperationException

Install Dir contains invalid path characters: {installDir}

Error message

Install Dir contains invalid path characters: {installDir}

What it means

ResolveAndValidateInstallPath checks the trimmed path against Path.GetInvalidPathChars() and throws if any illegal character (e.g. <, >, |, ", or control chars) is present. These characters cannot appear in a real filesystem path.

Source

Thrown at MCPForUnity/Editor/Setup/SkillSyncService.cs:673

                {
                    continue;
                }

                Directory.Delete(directory, false);
            }
        }

        internal static string ResolveAndValidateInstallPath(string installDir)
        {
            if (string.IsNullOrWhiteSpace(installDir))
            {
                throw new InvalidOperationException("Install Dir is empty.");
            }

            var trimmed = installDir.Trim();
            if (trimmed.IndexOfAny(Path.GetInvalidPathChars()) >= 0)
            {
                throw new InvalidOperationException($"Install Dir contains invalid path characters: {installDir}");
            }

            string expandedPath;
            try
            {
                expandedPath = ExpandPath(trimmed);
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException($"Install Dir is invalid and cannot be resolved: {installDir}", ex);
            }

            if (string.IsNullOrWhiteSpace(expandedPath))
            {
                throw new InvalidOperationException("Install Dir resolved to an empty path.");
            }

            return expandedPath;

View on GitHub (pinned to c21bf496bc)

Solutions

1. Remove any of <, >, |, ", or control characters from the path.
2. Use a plain filesystem path with normal separators.
3. If using a template variable, ensure it is resolved before passing the value.

Example fix

// before
var installDir = "<project>/Skills";
// after
var installDir = "/Users/me/Projects/MyGame/Skills";

if (installDir.IndexOfAny(Path.GetInvalidPathChars()) >= 0)
{
    throw new ArgumentException($"Install directory contains invalid characters: {installDir}");
}

When it happens

Trigger: User pasted a URL or a copy-paste artifact containing special characters; a template/variable was not substituted and left a literal like '<project>'; input mixed path separators with disallowed chars.

Common situations: Placeholder syntax left in the path; pasted from a rich-text source that inserted smart quotes; URL fragment mistaken for a path.

Related errors

• Install Dir is empty.
• Source path cannot be empty.
• Selected folder does not exist.
• The selected uvx executable does not exist
• The selected Claude CLI executable does not exist

AI-assisted analysis of CoplayDev/unity-mcp@c21bf496bc (2026-08-13). Data as JSON: /api/errors/9f71fd188230eb3d. Report an issue: GitHub.