Error: Objects are not valid as a child. Encountered an object with the keys {0,1,2,3,4,5,6,7,8,9,10}.

[lfre]

Repro: https://github.com/lfre/preact-render-to-string-issue

preact-render-to-string 5.2.4+ throws errors in Development mode. Three things cause this:

• The esmExternals experiment property is set to false. This is needed to resolve related issues: https://github.com/preactjs/next-plugin-preact/issues/53 https://github.com/preactjs/next-plugin-preact/issues/25
• The preact/debug entry added in development. Ref
• The usage of interpolated variables in components. E.g:

function MyComponent({ name }) {
    return <div>My {name}</div>
}

[bfeister]

Same issue on my end, in my case import useSWR from 'swr' is the cause (as opposed to preact-render-to-string )

[lfre]

Confirming this is fixed on preact-render-to-string 5.2.6 👍