React 16 warning "warning.js:36 Warning: Did not expect server HTML to contain a <div> in <div>."

Just change express response from

<body>
    <div id="root">
        ${markup}
    </div>
</body>

<body>
    <div id="root">${markup}</div>
</body>

Remove space between tags

Looking for that error in the react code it seems that this happens when the SSR html can't be rehydrated.

https://github.com/facebook/react/blob/7a60a8092144e8ab2c85c6906dd4a7a5815cff1f/src/renderers/dom/fiber/ReactDOMFiberComponent.js#L1022

So you are somehow initially rendering a different tree on the client vs the server.

Related