HTML Guide
A character has been found in the document that is not allowed in the charset encoding being used.
Related W3C validator issues
The document has been declared to use a windows-1251 charset but the actual contents seems to be utf-8. You should update the charset to that like in this example:
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">In order to define the charset encoding of an HTML document, both of these options are valid, but only one of them must appear in the document:
<!-- This is the preferred way -->
<meta charset="UTF-8">
<!-- This is the older way, also valid -->
<meta http-equiv="content-type" content="text/html; charset=UTF-8">The issue here is related to the encoding of URLs. In HTML and URLs, special characters that have specific meanings need to be encoded to ensure that the URL is interpreted correctly. This process converts characters to their percent-encoded form, where a character is replaced by % followed by two hexadecimal digits representing the ASCII code of the character.
Explanation:
- The action attribute of a <form> element specifies where to send the form-data when a form is submitted.
- If the URL contains special characters (e.g., spaces, <, >, #, %, etc.), they need to be percent-encoded. For instance, a space character is encoded as %20.
- In this case, the validator is complaining about a % sign that is not correctly followed by two hexadecimal digits, which typically happens if the URL was not properly encoded.
How to Fix:
- Check the URL: Look for any raw special characters that need encoding.
- Correctly Encode the URL: Use online tools or libraries that provide URL encoding support to ensure that the URL is correctly percent-encoded.
Example:
Suppose you have the following incorrect form tag:
<form action="submit%data.html">
<!-- form elements here -->
</form>The % in submit%data.html should be followed by two hexadecimal digits. If %data was intended to be a part of the URL, it should be encoded properly. Here is how to correct it:
<form action="submit%25data.html">
<!-- form elements here -->
</form>If % should represent data, replace % with %25, which is the percent-encoded form of %. Always verify each special character is correctly encoded. Using this approach ensures that the URL in the action attribute is valid according to HTML standards.
The href attribute of an <a> element contains an invalid character, that should be properly encoded as a URI percent-encoded character.
The href attribute of the a element contains an invalid backslash character, which is not permitted in URLs.
According to the WHATWG HTML living standard, the href attribute must contain a valid URL. URLs use forward slashes (/) for path separators, and backslashes are not allowed as they can cause browsers and validators to misinterpret the address. Backslashes often arise when file paths are copied from Windows environments.
Correct Usage:
- Always use forward slashes / in your URLs.
- Remove any backslashes from href values.
Example of incorrect usage:
<a href="images\picture.jpg">View Picture</a>Corrected example:
<a href="images/picture.jpg">View Picture</a>An illegal character has been found for the “href” attribute on the “link” element.
To fix this issue, find the “link” element in question and make sure that the “href” attribute contains a valid URL without any illegal characters.
Here’s some example HTML code of a link element:
<!DOCTYPE html>
<html>
<head>
<title>My Webpage</title>
<link rel="stylesheet" href="styles/main.css">
</head>
<body>
<h1>Welcome to my webpage!</h1>
<p>Here is some content...</p>
</body>
</html>In the above example, the link element has a valid href attribute value of styles/main.css. Make sure that your href attribute values don’t contain any illegal characters.
The src attribute on an <img> element contains an invalid character, that should be properly encoded as a URI percent-encoded character.
A <meta> tag has been found in the document stating that the charset is windows-1251, but it actually is utf-8. You should update the tag to reflect the actual encoding of the document, for example:
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">A <meta> tag has been found in the document stating that the charset is windows-1252, but it actually is utf-8. You should update the tag to reflect the actual encoding of the document, for example:
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">The accept attribute may be specified to provide browsers with a hint of what file types will be accepted on an <input> element. It expects a comma-separated list of allowed file types. Refer to the list of media types to check the accepted tokens. In this example, the first line is invalid while the second is valid:
<input name='file' type='file' accept='doc, docx, pdf' />
<input name='file' type='file' accept='text/doc, text/docx, application/pdf' />