BabylonJS/Babylon.js · error

No active scene.

Error message

No active scene.

What it means

The `start-perf-instrumentation` CLI command requires an active scene from the inspector's scene context. When no scene has been loaded/opened (sceneContext.currentScene is null), there is nothing to instrument, so the command throws this error instead of silently starting no-op instrumentation.

Source

Thrown at packages/dev/inspector-v2/src/services/cli/statsCommandService.ts:34

    consumes: [BridgeCommandRegistryIdentity, SceneContextIdentity],
    factory: (commandRegistry, sceneContext) => {
        let sceneInstrumentation: SceneInstrumentation | undefined;
        let engineInstrumentation: EngineInstrumentation | undefined;

        function disposeInstrumentation() {
            sceneInstrumentation?.dispose();
            sceneInstrumentation = undefined;
            engineInstrumentation?.dispose();
            engineInstrumentation = undefined;
        }

        const startPerfReg = commandRegistry.addCommand({
            id: "start-perf-instrumentation",
            description: "Start scene and engine performance instrumentation for frame stats collection.",
            executeAsync: async () => {
                const scene = sceneContext.currentScene;
                if (!scene) {
                    throw new Error("No active scene.");
                }

                // Dispose any stale instrumentation (e.g. scene changed).
                if (sceneInstrumentation && sceneInstrumentation.scene !== scene) {
                    disposeInstrumentation();
                }

                if (sceneInstrumentation) {
                    return "Performance instrumentation is already running.";
                }

                sceneInstrumentation = new SceneInstrumentation(scene);
                sceneInstrumentation.captureActiveMeshesEvaluationTime = true;
                sceneInstrumentation.captureRenderTargetsRenderTime = true;
                sceneInstrumentation.captureFrameTime = true;
                sceneInstrumentation.captureRenderTime = true;
                sceneInstrumentation.captureInterFrameTime = true;
                sceneInstrumentation.captureParticlesRenderTime = true;

View on GitHub (pinned to 0592b347b8)

Solutions

1. Load or create a scene first, then run start-perf-instrumentation
2. Wait for scene initialization (sceneContext.currentScene to be non-null / scene.whenReadyAsync()) before invoking the command
3. If a scene was disposed, re-create or re-select it in the inspector before instrumenting
4. Add a guard in automation scripts that polls for an active scene before issuing CLI commands

Example fix

// before
await cli.run("start-perf-instrumentation", {});
// after
if (!sceneContext.currentScene) {
    await waitForScene(sceneContext);
}
await cli.run("start-perf-instrumentation", {});

if (!sceneContext.currentScene) {
    throw new Error("Cannot start instrumentation: no active scene. Load a scene first.");
}
await cli.run("start-perf-instrumentation", {});

function hasActiveScene(ctx: { currentScene: BABYLON.Scene | null }): ctx is { currentScene: BABYLON.Scene } {
    return ctx.currentScene !== null && !ctx.currentScene.isDisposed;
}

try {
    await cli.run("start-perf-instrumentation", {});
} catch (err) {
    if (String(err).includes("No active scene")) {
        await loadOrAwaitScene();
        await cli.run("start-perf-instrumentation", {});
    } else {
        throw err;
    }
}

When it happens

Trigger: Running start-perf-instrumentation before any scene is created or attached in the inspector; after the engine/scene was disposed; in a headless session where scene initialization hasn't completed yet.

Common situations: Calling the CLI command during tool startup before the playground/app loads a scene; scene disposal racing with instrumentation commands; automating the inspector without first awaiting scene initialization.

Related errors

• No active scene.
• No active scene.
• No active scene.
• Cannot upload to a 2D array texture that is not attached to
• No camera available for screenshot.

AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/38b8353f9a2e89ee. Report an issue: GitHub.