vercel/next.js · error

Warning: <title> should not be used in _document.js's <Head>

Error message

Warning: <title> should not be used in _document.js's <Head>. https://nextjs.org/docs/messages/no-document-title

What it means

In _document's Head render (dev only), children are scanned for a <title> element (react-helmet usage via data-react-helmet is exempted) and this warning is logged because page titles belong in the page or _app component, not _document's <Head>, where they cannot be per-page correct.

Source

Thrown at packages/next/src/pages/_document.tsx:668

          if (child) {
            otherHeadElements.push(
              React.cloneElement(child, { 'data-next-head': '' })
            )
          }
        }
      })
      head = cssPreloads.concat(otherHeadElements)
    }
    let children: React.ReactNode[] = React.Children.toArray(
      this.props.children
    ).filter(Boolean)
    // show a warning if Head contains <title> (only in development)
    if (process.env.NODE_ENV !== 'production') {
      children = React.Children.map(children, (child: any) => {
        const isReactHelmet = child?.props?.['data-react-helmet']
        if (!isReactHelmet) {
          if (child?.type === 'title') {
            console.warn(
              "Warning: <title> should not be used in _document.js's <Head>. https://nextjs.org/docs/messages/no-document-title"
            )
          } else if (
            child?.type === 'meta' &&
            child?.props?.name === 'viewport'
          ) {
            console.warn(
              "Warning: viewport meta tags should not be used in _document.js's <Head>. https://nextjs.org/docs/messages/no-document-viewport-meta"
            )
          }
        }
        return child
        // @types/react bug. Returned value from .map will not be `null` if you pass in `[null]`
      })!
      if (this.props.crossOrigin)
        console.warn(
          'Warning: `Head` attribute `crossOrigin` is deprecated. https://nextjs.org/docs/messages/doc-crossorigin-deprecated'
        )

View on GitHub (pinned to 0eb3775416)

Solutions

  1. Use `next/head` in your page components for <title> instead of _document's <Head>.
Defensive patterns

Strategy: validation

When it happens

Trigger: Thrown at packages/next/src/pages/_document.tsx:668 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/next.js@0eb3775416 (2026-08-19). Data as JSON: /api/errors/ee66e1863ec204e3. Report an issue: GitHub.