TypeError: Cannot read property '_documentProps' of null

Bug report

Describe the bug

TypeError: Cannot read property '_documentProps' of null

This gets thrown in the render method of Head :

render() {
    var {
      styles,
      ampPath,
      inAmpMode,
      assetPrefix,
      hybridAmp,
      canonicalBase,
      __NEXT_DATA__,
      dangerousAsPath,
      headTags
    } = this.context._documentProps;

Works fine in development but when building and running the build version it crashes

To Reproduce

Steps to reproduce the behavior, please provide code snippets or a repository:

I understand this might be something related to my setup. I am using typescript and nextjs.

Expected behavior

No error thrown.

System information

• OS: macOS
• Browser (if applies) chrome (any)
• Version of Next.js: 9.1.4

Additional context

App works fine in 9.0.4 but I have a depenency that is throwing a vulnerability warning…and shouldn’t be a big update (I assumed).

The issue alwways shows itself in the first element inside the Document in pages/_document. In this case its “Head” but if I remove Head then it shows itself in “Main”. Somehow this context is not getting populated…only when building (works in development)

This is the getInitialProps of my _document page :

public static async getInitialProps(context: CustomDocumentContext) {
    const sheet = new ServerStyleSheet();
    const renderPage = context.renderPage;

    try {
      context.renderPage = () => {
        const enhancer = App => props => {
          return sheet.collectStyles(<App {...props} />);
        };

        return renderPage(enhancer);
      };

      const initialProps: any = await BaseDocument.getInitialProps(context);
      const { language, locale, localeData } = context.req;

      return {
        ...initialProps,
        language,
        locale,
        localeData,
        styles: (
          <>
            {initialProps.styles}
            {sheet.getStyleElement()}
          </>
        ),
      };
    } finally {
      // @ts-ignore
      sheet.seal();
    }
  }

[phoenisx]

I faced the same issue, not sure if this is related. But, the issue was caused due to improper import.

Instead of import { Head } from 'next/document', it should be import Head from 'next/head', if anybody is trying to import Head inside individual pages, and not in _document, as stated in docs.

[andresmejia3]

@Shub1427 You’re a beauty, thanks!