vercel/next.js · error

'router' and 'Component' can not be returned in getInitialPr

Error message

'router' and 'Component' can not be returned in getInitialProps from _app.js https://nextjs.org/docs/messages/cant-override-next-props

What it means

Development-server guard in renderToHTMLImpl: after calling _app's getInitialProps the returned props are checked for router or Component keys. Those are framework-provided props that Next.js itself injects; returning them from _app.js would override framework values, so the dev server rejects the response shape.

Source

Thrown at packages/next/src/server/render.tsx:1319

        if (ctx.err && ErrorDebug) {
          // Always start rendering the shell even if there's an error.
          if (renderShell) {
            renderShell(App, Component)
          }

          const html = await renderToString(
            <Body>
              <ErrorDebug />
            </Body>
          )
          return { html, head }
        }

        if (
          process.env.__NEXT_DEV_SERVER &&
          (props.router || props.Component)
        ) {
          throw new Error(
            `'router' and 'Component' can not be returned in getInitialProps from _app.js https://nextjs.org/docs/messages/cant-override-next-props`
          )
        }

        const { App: EnhancedApp, Component: EnhancedComponent } =
          enhanceComponents(options, App, Component)

        const stream = await renderShell(EnhancedApp, EnhancedComponent)
        await stream.allReady
        const html = await streamToString(stream)

        return { html, head }
      }
      const documentCtx = { ...ctx, renderPage }
      const docProps: DocumentInitialProps = await loadGetInitialProps(
        Document,
        documentCtx
      )

View on GitHub (pinned to 89d017eac4)

Solutions

  1. Remove `router` and `Component` keys from the object returned by `getInitialProps` in pages/_app.js; Next.js sets these itself.
Defensive patterns

Strategy: validation

When it happens

Trigger: Thrown at packages/next/src/server/render.tsx:1321 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/next.js@89d017eac4 (2026-08-19). Data as JSON: /api/errors/764a18b37345feb1. Report an issue: GitHub.