BabylonJS/Babylon.js · error

No active scene.

Error message

No active scene.

What it means

Thrown by the 'start-perf-trace' inspector CLI command when sceneContext.currentScene is null/undefined. Performance tracing instruments a live Babylon scene, so there is nothing to trace without an active scene. This fails fast before the perf collector is started.

Source

Thrown at packages/dev/inspector-v2/src/services/cli/perfTraceCommandService.ts:25

import "core/Misc/PerformanceViewer/performanceViewerSceneExtension";

/**
 * Service that registers CLI commands for performance tracing using the PerformanceViewerCollector.
 * start-perf-trace begins collecting data, stop-perf-trace stops and returns the collected data as JSON.
 */
export const PerfTraceCommandServiceDefinition: ServiceDefinition<[], [IBridgeCommandRegistry, ISceneContext]> = {
    friendlyName: "Perf Trace Command Service",
    consumes: [BridgeCommandRegistryIdentity, SceneContextIdentity],
    factory: (commandRegistry, sceneContext) => {
        let perfCollector: PerformanceViewerCollector | undefined;

        const startReg = commandRegistry.addCommand({
            id: "start-perf-trace",
            description: "Start collecting performance trace data.",
            executeAsync: async () => {
                const scene = sceneContext.currentScene;
                if (!scene) {
                    throw new Error("No active scene.");
                }

                if (perfCollector?.isStarted) {
                    return "Performance trace is already running.";
                }

                perfCollector = scene.getPerfCollector();
                perfCollector.stop();
                perfCollector.clear(false);
                perfCollector.addCollectionStrategies(...DefaultPerfStrategies);
                perfCollector.start(true);

                return "Performance trace started.";
            },
        });

        const stopReg = commandRegistry.addCommand({
            id: "stop-perf-trace",

View on GitHub (pinned to 0592b347b8)

Solutions

1. Create/switch to a scene first (run the scene-creation command or wait for app initialization) and retry start-perf-trace.
2. If scripting, gate the trace start on scene readiness: await the app's 'scene ready' event before invoking the command.
3. Verify the inspector is attached to the same sceneContext the application actually uses (not a detached second instance).

Example fix

// before
await execute("start-perf-trace", {}); // scene not created yet
// after
await onSceneReady();
await execute("start-perf-trace", {});

if (!sceneContext.currentScene) throw new Error("Cannot start perf trace: no active scene. Create a scene first.");

function hasActiveScene(ctx: { currentScene: unknown }): boolean { return ctx.currentScene != null; }

try {
  await startPerfTrace();
} catch (e) {
  if (e instanceof Error && e.message === "No active scene.") {
    await waitForSceneReady();
    await startPerfTrace();
  } else throw e;
}

When it happens

Trigger: Executing 'start-perf-trace' before any scene has been created, or after the scene was disposed/cleared, or when the inspector is attached to a context whose sceneContext was never wired to a running engine.

Common situations: Running the inspector/CLI agent at startup before the engine creates the first scene; scene disposed during hot-reload; connecting the inspector to a headless bootstrap that never initializes a scene.

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/c5624e0e9a21c1ff. Report an issue: GitHub.