remotion-dev/remotion · error · Error

Mediabunny did not return an output buffer.

Error message

Mediabunny did not return an output buffer.

What it means

After `recording.source.close()` and `await recording.output.finalize()`, the code expects `recording.target.buffer` to be populated by Mediabunny's `BufferTarget`. If the buffer is falsy, finalization produced no data. This is a defensive guard against Mediabunny silently returning an empty result despite a successful finalize.

Source

Thrown at packages/canvas-capture-extension/src/recorder.ts:336

const finalizeRecording = async (
	recording: RecordingState,
	filename: string,
	format: CaptureFormat,
): Promise<File> => {
	await recording.lastFramePromise;
	if (recording.hasEncodingError) {
		throw recording.encodingError;
	}

	if (recording.frameCount === 0) {
		throw new Error('No frames were added to the canvas recording.');
	}

	recording.source.close();
	await recording.output.finalize();

	if (!recording.target.buffer) {
		throw new Error('Mediabunny did not return an output buffer.');
	}

	const captureData = JSON.stringify({
		startedAt: recording.startedAt,
		endedAt: performance.now(),
		captureMetadata: recording.captureMetadata,
		mouseMovements: recording.mouseMovements,
		pointerClicks: recording.pointerClicks,
	});

	const {
		ALL_FORMATS,
		BufferSource,
		BufferTarget,
		Conversion,
		Input,
		Mp4OutputFormat,
		Output,

View on GitHub (pinned to 78fe4bb3fd)

Solutions

1. Upgrade or pin a known-good Mediabunny version.
2. Inspect `recording.encodingError` and `hasEncodingError` for the real cause.
3. Re-run the capture; if persistent, capture debug info from the Mediabunny conversion.
4. Report with the Mediabunny version and capture parameters.

try {
  await recorder.stopRecording();
} catch (e) {
  if (e instanceof Error && /did not return an output buffer/.test(e.message)) {
    logMediabunnyVersion();
    // re-record with a fresh session; do not reuse state.
  }
  throw e;
}

When it happens

Trigger: Mediabunny's `BufferTarget` did not accumulate bytes — e.g., the muxer/encoder produced no output despite frameCount > 0; a Mediabunny version mismatch or internal error left the buffer undefined; finalize resolved but never wrote to the target.

Common situations: Mediabunny version regression; encoding silently dropped samples; a corrupted Mediabunny build; an unsupported codec configuration that did not raise `encodingError`.

Related errors

• Mediabunny remux did not return an output buffer.
• ${label} encoding is not supported at ${size.width}×${size.h
• No frames were added to the canvas recording.
• The display canvas would be ${displayWidth}×${displayHeight}
• The encoded frame would be ${outputSize.width}×${outputSize.

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/5e06b4348ee7d3d2. Report an issue: GitHub.