HTML Checking for Large Sites
Rocket Validator automatically scans your sites for accessibility issues using the W3C Validator,
hosted on our own servers and integrated into our web crawler.
25,000 HTML checks per month. Is that enough for your site?
Save time using our automated web checker. Let our crawler check your web pages on the W3C Validator.
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
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>Learn more:
<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/?s=some term">invalid</a>
<a href="https://example.com/?s=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 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>Learn more:
The <a> element requires either a href attribute, or a role attribute.
Learn more:
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.
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>
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>
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.
Learn more:
Still checking your large sites one page at a time?
Save time using our automated web checker. Let our crawler check your web pages on the W3C Validator.