remotion-dev/remotion · error

Multiple composition with id

Error message

Multiple composition with id ${comp.id} are registered.

What it means

Thrown by CompositionManagerProvider.registerComposition when a second composition is registered with an id that already exists in the compositions list. Remotion uses ids as the unique key for the CLI (`--props`, `render <id>`), for Studio routing, and for render selection, so duplicates would create ambiguous resolution. The check fires inside the setCompositions updater so it runs once per composition registration.

Solutions

1. Search your Root for the id reported in the message (`${comp.id}`) and rename the duplicate.
2. If generating compositions from data, derive the id from a guaranteed-unique field (e.g. slug, uuid) rather than title.
3. Remove or rename the older entry so each id appears exactly once across <Composition>, <Still>, and <Folder>.
4. Run `bunx remotion compositions` after the fix to confirm each id is listed exactly once.

Example fix

// before
<Composition id="intro" component={Intro} ... />
<Composition id="intro" component={IntroV2} ... />
// after
<Composition id="intro" component={Intro} ... />
<Composition id="intro-v2" component={IntroV2} ... />

const ids = compositions.map((c) => c.id);
const dupes = ids.filter((id, i) => ids.indexOf(id) !== i);
if (dupes.length > 0) {
  throw new Error(`Duplicate composition ids: ${dupes.join(', ')}`);
}

const hasUniqueIds = (list: ReadonlyArray<{id: string}>): boolean =>
  new Set(list.map((c) => c.id)).size === list.length;

When it happens

Trigger: Two `<Composition id="x" />` entries in the same Root; dynamically generating compositions from an array where ids collide; copy-paste of a Composition block without renaming the id; a Composition and a Still sharing the same id.

Common situations: Large Root files where ids drift; refactor that splits a file and duplicates an id; programmatic composition generation from a list that has duplicate keys; migration from one project template that leaves a leftover Composition.

Related errors

• No id for composition passed.
• Composition id can only contain a-z, A-Z, 0-9, CJK…
• 'composition' is required.
• " " must be an object, an array was passed "` : ''}
• " " must be an object, but you passed a value of type

AI-assisted analysis of remotion-dev/remotion@a6a7485a9a (2026-09-02). Data as JSON: /api/errors/d719c76fe3a90081. Report an issue: GitHub.

Appendix: source

Thrown at packages/core/src/CompositionManagerProvider.tsx:102

				return updated;
			});
		},
		[],
	);

	const registerComposition = useCallback(
		<Schema extends AnyZodObject, Props extends Record<string, unknown>>(
			comp: TComposition<Schema, Props>,
		) => {
			const orderKey = getCompositionAndFolderOrderKey({
				type: 'composition',
				id: comp.id,
			});
			const internalOrder = nextInternalOrderRef.current++;
			internalOrderRef.current.set(orderKey, internalOrder);
			updateCompositions((comps) => {
				if (comps.find((c) => c.id === comp.id)) {
					throw new Error(
						`Multiple composition with id ${comp.id} are registered.`,
					);
				}

				return [
					...comps,
					{
						...comp,
						order: committedOrderRef.current?.get(orderKey) ?? internalOrder,
					},
				] as AnyComposition[];
			});
		},
		[updateCompositions],
	);

	const unregisterComposition = useCallback((id: string) => {
		internalOrderRef.current.delete(

View on GitHub (pinned to a6a7485a9a)