What does this mean?

Do not link to an anchor on the page that does not exist. For example: linking to #content without a valid destination such as <body id="content"></body>.

A common web design pattern is to use a named anchor to show an element via JavaScript, e.g.

<a href="#foo" onclick="$('.bar').toggle();">Click me</a>
<div class="bar">
    This is some content.

In these cases, the anchor (#foo) should point to the id of the hidden element:

<a href="#foo" onclick="$('#foo').toggle();">Click me</a>
<div id="foo">
    This is some content.

This way the semantic intent of the link is preserved, even without JavaScript. Note that doing so may require modification to your script, to prevent automatic scrolling to the named anchor.

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How close this website is to fixing this issue.

HTML Found on page Issues
<a id="scrollUp" href="#top" style="display: none; position: absolute; z-index: 2147483647; bottom: 85px; right: 40px;"><span class="visuallyhidden">scroll down</span></a> 50
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<a href="#DynamicJumpMenuManager_1_Anchor_4">What we're doing as a result of the Grenfell Tower incident</a> 1
<a class="close" href="#close">Close</a> 1
<a href="#DynamicJumpMenuManager_1_Anchor_8">Advice for local authorities</a> 1
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59 distinct issues were found in the sample of 50 web pages. Only the first 10 issues are shown here.
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