HTML Guide for bad value

The src attribute value is malformed, check that it doesn’t contain extraneous characters.

For example, this is invalid because the URL in the src attribute contains a space in between the https: and // parts:

<a href="https: //example.com">Some link</a>

To fix this issue, you can try removing the space after “https:” in the URL in the src attribute:

<a href="https://example.com">Some link</a>

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.

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>

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">

XML 1.0 names, typically used for the id attribute of elements, must comply with specific constraints, such as:

• Must start with a letter or underscore _
• Subsequent characters can be letters, digits, hyphens -, underscores _, and periods .
• Cannot contain any spaces or special characters

Here’s an example of an invalid name for an ID:

<svg>
  <g id="Group 270">
    <!-- Content inside the group element -->
  </g>
</svg>

This can be fixed by avoiding whitespace inside the name, like this:

<svg>
  <g id="group-270">
    <!-- Content inside the group element -->
  </g>
</svg>

In this example, the id attribute value Group 270 has been changed to group-270 to follow the rules for XML 1.0 names.

The text-transform CSS property specifies how to capitalize an element’s text. It can be used to make text appear in all-uppercase or all-lowercase, or with each word capitalized.

Examples of valid values for this property are:

text-transform: none;
text-transform: capitalize;
text-transform: uppercase;
text-transform: lowercase;
text-transform: full-width;
text-transform: full-size-kana;