Now you can access logo because it is a static file which is rendered in HTML (img tag- browser resolves /logo.png to the root). It doesn't need any fetching or parsing but when it comes to react-simple-maps while accessing /topo.json the fetch() fails so it displays an unexpected error, to avoid this try using absolute url ex geography = { new URL('/topo.json', window.location.origin).toString() }, this ensures fetch always reach the path.