This usually means that the user mixed up our lowercase/uppercase naming convention; see https://github.com/facebook/react/pull/3429#issuecomment-85166440.

We could add a message like

> Warning: The tag <commentBox> is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

We'd check this only once per tag and only in development mode.

render() {
          return <a>{this.props.children}</a>;
        }
      }
      ReactTestUtils.renderIntoDocument(<Link><div><Link /></div></Link>);
      expectDev(console.error.calls.count()).toBe(6);
      expectDev(
        normalizeCodeLocInfo(console.error.calls.argsFor(5)[0]),
      ).toContain(
        ReactDOMFeatureFlags.useFiber
          ? '\n    in a (at **)' +
              '\n    in Link (at **)' +
              '\n    in div (at **)' +
              '\n    in a (at **)' +
              '\n    in Link (at **)'
          : 'See Link > a > ... > Link > a.',
      );
    });
    it('should warn about incorrect casing on properties (ssr)', () => {
      spyOn(console, 'error');
      ReactDOMServer.renderToString(
        React.createElement('input', {type: 'text', tabindex: '1'}),
      );
      expectDev(console.error.calls.count()).toBe(1);
      expectDev(console.error.calls.argsFor(0)[0]).toContain('tabIndex');
    });
    it('should warn about incorrect casing on event handlers (ssr)', () => {