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href attribute on the
link element must not be empty.
Related W3C validator issues
<link> element has been found in an invalid body context. Check the attributes of the
<link> element and ensure it’s not within the
If the element is within the
<head> section, it may have been interpreted as a
body context depending on previous elements. For example, while this
<link> element is valid per se and is in the
<head> section, it is deemed invalid because the previous
<img> element made the validator consider it a
<!DOCTYPE html> <html lang=""> <head> <title>Test</title> <img src="photo.jpg" alt="A smiling cat" /> <link rel="canonical" href="https://example.com/" /> </head> <body> <p>Some content</p> </body> </html>
If we fix that document and move the
<img> tag within the body, the issue raised about
<meta> disappears because it’s now in a valid context:
<!DOCTYPE html> <html lang=""> <head> <title>Test</title> <link rel="canonical" href="https://example.com/" /> </head> <body> <p>Some content</p> <img src="photo.jpg" alt="A smiling cat" /> </body> </html>
<iframe> element allows to embed an HTML document inside another HTML document, and its
src attribute is indicated the source URL of the embedded web page. The
src attribute is a required attribute, so it cannot be blank.
<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: firstname.lastname@example.org">This is wrong as it contains an space</a> <a href="mailto:email@example.com">This is OK</a>
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>
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>
href attribute on an element
<a> contains a
| character, also known as vertical pipe.
This character is not allowed and should be replaced by its encoded alternative
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
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.
screen. Used for computer, tablets or smartphone screens.
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
<link rel="icon" type="image/png" href="favicon.png">
<a> element requires either a
href attribute, or a
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