remotion-dev/remotion · error · TypeError

"region" parameter must be a string, but is ${JSON.stringify

Error message

"region" parameter must be a string, but is ${JSON.stringify(region)}

What it means

Thrown by validateRegion() when the region argument is not a string. This is the type guard before the GCP_REGIONS membership check. Region is required for nearly every Cloud Run API to address resources in the correct Google Cloud location.

Source

Thrown at packages/cloudrun/src/shared/validate-region.ts:6

import type {GcpRegion} from '../pricing/gcp-regions';
import {GCP_REGIONS} from '../pricing/gcp-regions';

export const validateRegion = (region: unknown) => {
	if (typeof region !== 'string') {
		throw new TypeError(
			`"region" parameter must be a string, but is ${JSON.stringify(region)}`,
		);
	}

	// check region is part of GCP_REGIONS list
	if (!GCP_REGIONS.includes(region as GcpRegion)) {
		throw new TypeError(
			`"region" parameter must be one of ${GCP_REGIONS.join(
				', ',
			)}, but is ${JSON.stringify(region)}`,
		);
	}

	return region as GcpRegion;
};

View on GitHub (pinned to 78fe4bb3fd)

Solutions

Pass a valid GCP region string such as 'us-east1'.
Default region when unset: const region = config.region ?? 'us-east1' (the package DEFAULT_REGION).
Validate config at startup.

Example fix

// before
const { REGION } = process.env; // undefined
await deployService({ region: REGION, ... });
// after
const region = process.env.REGION ?? 'us-east1';
await deployService({ region, ... });

Defensive patterns

Strategy: type-guard

Validate before calling

import { validateRegion } from '@remotion/cloudrun/shared';
validateRegion(region);

Type guard

function isRegionString(v: unknown): v is string {
  return typeof v === 'string';
}

Try / catch

const region = typeof inputRegion === 'string' ? inputRegion : 'us-east1';

Prevention

Default region to 'us-east1' (the package default) when unset.
Type your config so region is always a string.
Assert env vars are set at process start.

When it happens

Trigger: Passing a non-string region (undefined, null, number, object) to any Cloud Run API that validates region.

Common situations: Region read from an unset env var; passing a config object instead of its region string property; destructuring typo leaving region undefined.

Related errors

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/3f862a3f00a3160e. Report an issue: GitHub.