Deprecated: The preferredRegion route segment config is deprecated. Remove the preferredRegion export from your route files. See the deprecation message for details.

The preferredRegion option allows you to specify the preferred deployment region for a route segment. This value is passed to your deployment platform.

export const preferredRegion = // string || string[]

export const preferredRegion = // string || string[]

• string: Deploy the route to a specific region. Available region codes are platform-specific. For example, 'iad1'.
• string[]: Deploy the route to multiple specific regions. The route is deployed to all listed regions, not a single one chosen from the list. For example, ['iad1', 'sfo1'].

Good to know:

• If a preferredRegion is not specified, it will inherit the option of the nearest parent layout. The root layout defaults to 'auto'.
• A child segment's value overrides the parent, values are not merged.
• Next.js passes the region values through to the deployment platform. The exact behavior and available region codes are platform-specific. Refer to your deployment platform's documentation for supported values.

Vercel

If deploying Next.js on Vercel, regions were previously only supported with export const runtime = 'edge', which is now deprecated. The following options can be passed:

• 'auto' (default): Uses the default region.
• 'global': Prefer deploying the route to all availableregions.
• 'home': Prefer deploying the route to the home region.

If an unsupported value is passed, an error will be thrown.

Source: docs/01-app/03-api-reference/03-file-conventions/02-route-segment-config/preferredRegion.mdx