About This HTML Issue
The path in an <area> element's href can't contain a literal space, so write each space as %20 or take it out of the URL.
An <area> defines one clickable region of an image map. The <map> element groups the areas under a name, and an <img> points to that map with usemap="#name". An <area> with an href is a link, and the URL Standard doesn't allow spaces anywhere in a URL path. The usual cause is a page or file name with a space in it, like /islands/north island.
Browsers percent-encode the space before following the link, so the click usually still works. A crawler or a script that reads the raw value may not, and the markup is invalid either way.
Replace each space with %20. If you control the target URLs, hyphens (north-island) make cleaner addresses that need no encoding at all. A space after the ? triggers a different message, Illegal character in query, and %20 fixes that one too.
Every <area> with an href also needs an alt attribute. Screen readers announce it as the link text for that region, and the validator reports a missing one as a separate error.
Invalid example
<img src="islands.png" alt="Map of the islands" usemap="#islands" width="600" height="400">
<map name="islands">
<area shape="rect" coords="20,40,180,160" href="/islands/north island" alt="North Island">
<area shape="rect" coords="220,200,400,320" href="/islands/south island" alt="South Island">
</map>
Valid example: spaces encoded as %20
<img src="islands.png" alt="Map of the islands" usemap="#islands" width="600" height="400">
<map name="islands">
<area shape="rect" coords="20,40,180,160" href="/islands/north%20island" alt="North Island">
<area shape="rect" coords="220,200,400,320" href="/islands/south%20island" alt="South Island">
</map>
Valid example: hyphens instead of spaces
<img src="islands.png" alt="Map of the islands" usemap="#islands" width="600" height="400">
<map name="islands">
<area shape="rect" coords="20,40,180,160" href="/islands/north-island" alt="North Island">
<area shape="rect" coords="220,200,400,320" href="/islands/south-island" alt="South Island">
</map>
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