CoplayDev/unity-mcp · error · Exception

GameObject '{go.name}' does not have a ProBuilderMesh compon

Error message

GameObject '{go.name}' does not have a ProBuilderMesh component.

What it means

Thrown by RequireProBuilderMesh when the target GameObject was found but does not have a ProBuilderMesh component. The tool uses reflection (GetComponent against _proBuilderMeshType) to locate the component, so the object must be an actual ProBuilder shape, not a standard Unity primitive or mesh.

Source

Thrown at MCPForUnity/Editor/Tools/ProBuilder/ManageProBuilder.cs:283

        internal static GameObject FindTarget(JObject @params)
        {
            return ObjectResolver.ResolveGameObject(@params["target"], @params["searchMethod"]?.ToString());
        }

        private static Component GetProBuilderMesh(GameObject go)
        {
            return go.GetComponent(_proBuilderMeshType);
        }

        internal static Component RequireProBuilderMesh(JObject @params)
        {
            var go = FindTarget(@params);
            if (go == null)
                throw new Exception("Target GameObject not found.");
            var pbMesh = GetProBuilderMesh(go);
            if (pbMesh == null)
                throw new Exception($"GameObject '{go.name}' does not have a ProBuilderMesh component.");
            return pbMesh;
        }

        internal static void RefreshMesh(Component pbMesh)
        {
            // ToMesh and Refresh have optional parameters (MeshTopology, RefreshMask) —
            // Type.EmptyTypes won't find them. Use name-only lookup with default args.
            var toMeshMethod = _proBuilderMeshType.GetMethod("ToMesh", Type.EmptyTypes)
                ?? _proBuilderMeshType.GetMethod("ToMesh", BindingFlags.Instance | BindingFlags.Public);
            toMeshMethod?.Invoke(pbMesh, toMeshMethod.GetParameters().Length > 0
                ? new object[toMeshMethod.GetParameters().Length]
                : null);

            var refreshMethod = _proBuilderMeshType.GetMethod("Refresh", Type.EmptyTypes)
                ?? _proBuilderMeshType.GetMethod("Refresh", BindingFlags.Instance | BindingFlags.Public);
            refreshMethod?.Invoke(pbMesh, refreshMethod.GetParameters().Length > 0
                ? new object[refreshMethod.GetParameters().Length]
                : null);

View on GitHub (pinned to c21bf496bc)

Solutions

1. Create the shape using the ProBuilder create_shape tool so it gets a ProBuilderMesh component.
2. Use ProBuilder's 'ProBuilderize' (or the tool's conversion action if available) to add a ProBuilderMesh to an existing mesh.
3. Verify with read_components that a ProBuilderMesh is attached before calling mesh-editing operations.
4. If the object is a standard primitive, replace it with a ProBuilder shape of the same type.

Example fix

// before: GameObject created via manage_gameobject
// then calling: manage_probuilder bevel on it
// after: create via ProBuilder first
params = {"action": "create", "shapeType": "Cube", "name": "MyShape"}

# Before calling ProBuilder mesh operations, verify the component exists
# Use read_components on the target and check for a ProBuilderMesh
def has_probuilder_mesh(components):
    return any(c.get('type') == 'ProBuilderMesh' for c in components)

try
{
    var mesh = RequireProBuilderMesh(@params);
}
catch (Exception ex) when (ex.Message.Contains("does not have a ProBuilderMesh"))
{
    return new ErrorResponse($"Target is not a ProBuilder shape. Create it via create_shape first.");
}

When it happens

Trigger: Calling a ProBuilder tool (bevel, extrude, set_material, etc.) on a standard Unity primitive (GameObject.CreatePrimitive), a custom mesh object, or a GameObject that has never been ProBuilder-ized. Also if the ProBuilder package is installed but the object was created without ProBuilder APIs.

Common situations: AI creates a GameObject via manage_gameobject (not ProBuilder) then tries to run ProBuilder operations on it; converting a standard mesh to ProBuilder was skipped; the ProBuilder package version exposes a different component type name.

Related errors

• Target GameObject not found.
• Could not read faces from ProBuilderMesh.
• Failed to resolve Scene view host view.
• {hostView.GetType().FullName}.GrabPixels(RenderTexture, Rect
• Face index {indices[i]} out of range (0-{facesList.Count - 1

AI-assisted analysis of CoplayDev/unity-mcp@c21bf496bc (2026-08-13). Data as JSON: /api/errors/5d61ddb5277118d8. Report an issue: GitHub.