CoplayDev/unity-mcp · error · InvalidOperationException

uvx not found. Install uv/uvx or set the override in Advance

Error message

uvx not found. Install uv/uvx or set the override in Advanced Settings.

What it means

GetUvxPathOrError() is a protected helper on McpClientConfiguratorBase used by JsonFileMcpConfigurator.GetManualSnippet() and other base-class methods. It calls MCPServiceLocator.Paths.GetUvxPath() and throws InvalidOperationException if the result is null or empty. GetUvxPath() returns null only when an explicit override is invalid and no system fallback exists; without an override it always returns at least the bare string 'uvx'.

Source

Thrown at MCPForUnity/Editor/Clients/McpClientConfiguratorBase.cs:61

        public virtual string GetSkillInstallPath() => null;

        public abstract string GetConfigPath();
        public abstract McpStatus CheckStatus(bool attemptAutoRewrite = true);
        public abstract void Configure();

        /// <summary>Default Unregister is a no-op. Override in JsonFileMcpConfigurator /
        /// ClaudeCliMcpConfigurator etc. where removal has a concrete implementation.</summary>
        public virtual void Unregister() { }

        public abstract string GetManualSnippet();
        public abstract IList<string> GetInstallationSteps();

        protected string GetUvxPathOrError()
        {
            string uvx = MCPServiceLocator.Paths.GetUvxPath();
            if (string.IsNullOrEmpty(uvx))
            {
                throw new InvalidOperationException("uvx not found. Install uv/uvx or set the override in Advanced Settings.");
            }
            return uvx;
        }

        protected string CurrentOsPath()
        {
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
                return client.windowsConfigPath;
            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
                return client.macConfigPath;
            return client.linuxConfigPath;
        }

        protected static bool ParentDirectoryExists(string configPath)
        {
            try
            {
                if (string.IsNullOrEmpty(configPath)) return false;

View on GitHub (pinned to c21bf496bc)

Solutions

Remove or correct the uvx path override in Advanced Settings.
Install uv/uvx system-wide so GetUvxPath() discovers it via ResolveUvxFromSystem().
If the override is the issue, clear it via EditorPrefs.DeleteKey(EditorPrefKeys.UvxPathOverride) or the Advanced Settings UI.

Defensive patterns

Strategy: validation

Validate before calling

string uvx = MCPServiceLocator.Paths.GetUvxPath();
if (string.IsNullOrEmpty(uvx))
{ ShowErrorAndGuideUser("uvx not found. Install uv or set override in Advanced Settings."); return; }

Try / catch

try { string snippet = configurator.GetManualSnippet(); }
catch (InvalidOperationException ex) when (ex.Message.Contains("uvx not found"))
{ snippet = "# Install uv/uvx first, then retry."; }

Prevention

Ensure uv is installed before generating manual snippets.
Validate the uvx path override after moving or renaming the binary.
Use the Advanced Settings diagnostic to verify uvx detection.

When it happens

Trigger: Any base-class code path that calls GetUvxPathOrError() — typically GetManualSnippet() on a JsonFileMcpConfigurator subclass — when GetUvxPath() returns null (invalid override, no system binary).

Common situations: The user clicks 'Copy Manual Snippet' or similar in the MCP for Unity UI while a stale uvx override is set. A CI environment where EditorPrefs carries a bad override from a prior run.

Related errors

AI-assisted analysis of CoplayDev/unity-mcp@c21bf496bc (2026-08-13). Data as JSON: /api/errors/d0a011679ef158e4. Report an issue: GitHub.