HTML Checking for Large Sites
Rocket Validator automatically checks your pages on the W3C Validator.
Bad value “mailto: X” for attribute “href” on element “a”: Illegal character in scheme data: space is not allowed.
<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>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 value contact is not a valid option for the autocomplete attribute on an <input> element.
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An <a> element has been found with an invalid href attribute, containing more than one # adjacent character.
The # is used to separate the fragment part of an URI (typically used to indicate a section within a document). For example, this is a valid link to a URI containing a fragment:
<a href="https://example.com/faqs#pricing">pricing</a>
The next example is invalid because it contains two adjacent # characters, so that the fragment part would be #pricing instead of pricing:
<a href="https://example.com/faqs##pricing">pricing</a>Learn more:
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 href attribute on the link element must not be empty.
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:
The href attribute on an <a> link contains a space character, which is not allowed. If you’re trying to link to a phone URL, review the href attribute to remove unallowed characters, as in this example:
<!-- Invalid as it contains a space character -->
<a href="tel: +123456789">call me</a>
<!-- Valid -->
<a href="tel:+123456789">call me</a>Source:
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 element <a> contains a character that is not allowed, and should be encoded.
Some typical examples include the pipe character | that should be replaced by its encoded alternative %7C , and the left square bracket [ that needs to be encoded as %5B.
The href attribute on an <a> tag contains an space, which is not allowed. Consider replacing space characters with “%20”.
The at symbol (@) should be percent-encoded as %40 in order to include it at an href attribute.
The href attribute on an element <link> contains a character that is not allowed, and should be encoded.
Some typical examples include the pipe character | that should be replaced by its encoded alternative %7C , and the left square bracket [ that needs to be encoded as %5B.
A <pattern> element has been found with an invalid ID. Check the format of the ID and ensure it does not start with a digit, full stop (.) or hyphen (-).
The <pattern> element is used within <svg> elements, which use XML 1.0 syntax. That syntax specifies that valid IDs only include designated characters (letters, digits, and a few punctuation marks), and do not start with a digit, a full stop (.) character, or a hyphen-minus (-) character.
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The media attribute on a <link> element has not been recognized.
This attribute specified what media the linked resource is optimized for. As an example, the following will link a general stylesheet, and a specific one for printing:
<head>
<link rel="stylesheet" type="text/css" href="general.css">
<link rel="stylesheet" type="text/css" href="print.css" media="print">
</head>Valid values for this attribute include:
-
all. Default, used for all media. -
print. Used for printers and print previews. -
screen. Used for computer, tablets or smartphone screens.
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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 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 value used to define the type of a link is not valid. You’re probably using a URL instead of a valid type.
Example of a valid type:
<link rel="icon" type="image/png" href="favicon.png">Read more:
The <a> element requires either a href attribute, or a role attribute.
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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>Attributes in HTML elements need to be separated by space, in this example the first line is invalid and the second one is valid:
<a href="page.php"class="big">link</a>
<a href="page.php" class="big">link</a>
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>.
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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