What causes "Params must be renderer" in remotion-dev/remotion?

Ensure the renderer Lambda is only invoked by the launch function with a payload of type ServerlessRoutines.renderer

Params must be renderer

Error message

Params must be renderer

What it means

The serverless renderer Lambda handler validates that the incoming payload has type === ServerlessRoutines.renderer before doing any work. Any other routine type dispatched to this handler is a programming/routing error, so it throws immediately.

Source

Thrown at packages/serverless/src/handlers/renderer.ts:72

	params: ServerlessPayload<Provider>;
	options: Options;
	logs: BrowserLog[];
	onStream: OnStream<Provider>;
	providerSpecifics: ProviderSpecifics<Provider>;
	insideFunctionSpecifics: InsideFunctionSpecifics<Provider>;
	onBrowserInstance: (browserInstance: LaunchedBrowser) => void;
	onMediaFiles:
		| ((options: {
				videoOutputLocation: string;
				audioOutputLocation: string | null;
				isAudioOnly: boolean;
				completedAt: number;
		  }) => Promise<void>)
		| null;
	cancelSignal: CancelSignal | null;
}): Promise<{}> => {
	if (params.type !== ServerlessRoutines.renderer) {
		throw new Error('Params must be renderer');
	}

	const chromiumOptions =
		insideFunctionSpecifics.normalizeChromiumOptions?.({
			chromiumOptions: params.chromiumOptions,
			logLevel: params.logLevel,
		}) ?? params.chromiumOptions;

	if (params.launchFunctionConfig.version !== VERSION) {
		throw new Error(
			`The version of the function that was specified as "rendererFunctionName" is ${VERSION} but the version of the function that invoked the render is ${params.launchFunctionConfig.version}. Please make sure that the version of the function that is specified as "rendererFunctionName" is the same as the version of the function that is invoked.`,
		);
	}

	const inputPropsPromise = decompressInputProps({
		bucketName: params.bucketName,
		expectedBucketOwner: options.expectedBucketOwner,
		region: insideFunctionSpecifics.getCurrentRegionInFunction(),

View on GitHub (pinned to b2f4e34732)

Solutions

Ensure the renderer Lambda is only invoked by the launch function with a payload of type ServerlessRoutines.renderer
Call renderMediaOnLambda()/renderOnLambda instead of invoking the Lambda directly so the correct payload is built
Check that rendererFunctionName points at the renderer function, not the orchestrator function
Inspect the invoking payload's `type` field in CloudWatch logs and fix the caller

Example fix

// before (manual invoke)
await lambda.send(new InvokeCommand({ FunctionName: rendererFn, Payload: JSON.stringify({ type: 'launch', ... }) }));
// after
await renderMediaOnLambda({ functionName: rendererFn, serveUrl, composition, region });

Defensive patterns

Strategy: validation

Validate before calling

if (payload.type === 'renderer') {
  await invokeRenderer(payload);
}

Type guard

const isRendererParams = (p: unknown): p is RendererParams =>
  typeof p === 'object' && p !== null && (p as {type?: string}).type === 'renderer';

Try / catch

try {
  await renderHandler({ inputProps, ... });
} catch (e) {
  if ((e as Error).message === 'Params must be renderer') {
    // wrong payload routed to renderer function; fix caller
  } else { throw e; }
}

Prevention

Never invoke the renderer Lambda manually; use renderMediaOnLambda()/renderOnLambda
Verify rendererFunctionName points to the renderer, not the launch function
Log and inspect payload.type before dispatch

When it happens

Trigger: Invoking the renderer function's renderHandler with a payload whose `type` field is not 'renderer' — e.g. sending a launch routine payload to the renderer function, hand-crafted Lambda invocations, or wrongly wired sqs/lambda routing.

Common situations: Manually invoking the Lambda for testing with wrong payload; mixing up launch vs renderer function names so a launch payload reaches rendererHandler; custom orchestration code that constructs its own params.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of remotion-dev/remotion@b2f4e34732 (2026-09-09). Data as JSON: /api/errors/9a6a00f87b806b00. Report an issue: GitHub.