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End tag “a” violates nesting rules.
An </a> end tag has been found to violate nesting rules. <a> tags can’t include other <a> tags inside. Most probable cause is an unclosed <a> tag, like in this example:
<a href="one.html">Page 1
<a href="two.html">Page 2</a>
Related W3C validator issues
A button element, or an element with the role=button attribute, is not allowed to be nested inside an <a> element.
An <a> element cannot contain a descendant element with the attribute tabindex.
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The href attribute of an <a> element contains an invalid character, that should be properly encoded as a URI percent-encoded character.
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The target attribute on <a> elements can’t be blank.
This attribute defines the browsing context for links, that is, where should the linked documents be opened. This was used extensively on the now deprecated <frame> element, so you could give the name of the frame to open the document in, but is now more used to force links to open in a separate tab or window using target="_blank". Another option is using a name, so the new browsing context can be referred to on subsequent clicks on links with the same target.
For example, this will force the links to open on a new tab:
<a href="https://example.com" target="_blank">will open a blank tab</a>
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The href attribute on an a tag expects a valid URL, but only http:// was found.
<a> tags can be used to link to an email address using the mailto protocol in the href attribute. Ensure that there is no space in the email address.
<a href="mailto: liza@example.com">This is wrong as it contains an space</a>
<a href="mailto:liza@example.com">This is OK</a>
Space characters are not allowed in href attributes. Instead, they should be converted to %20. In this example, the first line is invalid and the second is valid:
<a href="https://example.com#some term">invalid</a>
<a href="https://example.com#some%20term">valid</a>
The href attribute on an <a> tag contains an space, which is not allowed. Consider replacing space characters with “%20”.
The value used in the target property of an <a> element has been identified as a keyword because it starts with an underscore _, but it’s not a valid keyword.
Values starting with an underscore for the target property are used for reserved keywords like _blank, _self, _parent or _top.
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The value provided on the type attribute of an a element is not a valid MIME type.
The type attribute expects a MIME type that hints at the linked URL’s format.
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The type attribute on <a> elements, when present, gives a hint on the MIME type of the linked resource, for example:
<a href="application/pdf" src="book.pdf">Read our book</a>
<a href="image/jpeg" src="photo.jpeg">See a photo</a>
That is, we’re talking about the type of the linked resource, not the type of the <a> element, as it’s sometimes misunderstood. The following example is invalid because button is not a valid MIME type.
<a href="/order.php" type="button">Submit</a>
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The <a> element requires either a href attribute, or a role attribute.
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A <div> tag has been found as a direct child of an <ul> tag, and this is not allowed. For example, <ul><div><li>item</li></div></ul> is not valid, but <ul><li><div>item</div></li></ul> is valid as the direct child of <ul> is <li>.
The element X is not allowed as a child element of Y. For example, a <ul> element cannot have a <div> child element.
An end tag </code> has been found violating nesting rules. Check other errors in the same document related to the <code> element, and fix the unallowed nested elements.
A closing </body> tag has been found, but there are unclosed elements before it. For example this has an unclosed <section> element:
<body>
<section>
</body>
An end tag </strong> has been found in an incorrect place within the document, violating nesting rules. A common case is closing it before closing other nested tags, for example:
<!-- This line is incorrect as the <strong> tag was closed before the nested <a> tag -->
<strong><a href="#">link</strong></a>
<!--- This line is OK as every end tag respects the nesting rules -->
<strong><a href="#">link</a></strong>
And end tag has been found that does not match the current open element. Check the context to fix the start and end tags.
An end tag has been found after the closing </body> tag, which breaks the expected HTML document structure.
Check out the document structure, a basic example follows:
<!DOCTYPE html>
<html lang="">
<head>
<title>Test</title>
</head>
<body>
<p></p>
</body>
</html>
An <a> tag can’t include other <a> tags inside. Most probable cause is an unclosed <a> tag, like in this example:
<a href="one.html">Page 1
<a href="two.html">Page 2</a>
An <a> element has been found in an invalid place within a <table> element.
For example, the following code would cause this issue:
<table>
<tr>
<a href="#">link</a>
</tr>
</table>
Instead, the <a> element should be inside a <td> element, as a <tr> can’t hold content directly:
<table>
<tr>
<td>
<a href="#">link</a>
</td>
</tr>
</table>An end tag for X has been found that does not correspond to a previous open tag. This usually happens when you close the same tag twice, for example:
<ul>
<li>item</li>
</ul>
</ul>
A button element, or an element with the role=button attribute, is not allowed to be nested inside an <a> element.
A <label> tag can’t be used inside an <a> tag. Consider using other tags like <span>.
A <label> element cannot contain other <label> as a descendant. Check for nested elements or closing tags that may have been misinterpreted, for example:
<label>name</label></label>
The <caption> element specifies the caption (or title) of a table. It’s not allowed for a <caption> to contain another table.
Links created with the <a> element no longer accept a shape attribute. In order to define image maps, use the <area> element instead.
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