HTML Guide

Using “windows-1252” instead of the declared encoding “iso-8859-1”.

Mismatch between the declared character encoding and the actual encoding confuses browsers and validators, and can cause character display issues.

The charset declaration in the meta tag should match the actual character encoding of your HTML file. Declaring "iso-8859-1" but saving the file as "windows-1252" (or vice versa) creates a conflict, since these encodings are similar but not identical. Moreover, UTF-8 is the recommended encoding for web documents, widely supported and preferable for modern websites.

To resolve the issue:

Decide which character encoding your HTML file should use.
Save your document with that encoding in your text editor or IDE.
Ensure your HTML declares the same encoding using the meta tag in the <head> section.

Example using UTF-8 (recommended):

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Example</title>
  <meta charset="utf-8">
</head>
<body>
  <p>Hello, world!</p>
</body>
</html>

If you specifically want iso-8859-1:

Save the file as iso-8859-1 in your editor.

Declare it in your HTML:

<!DOCTYPE html>
<html lang="en">
<head>
<title>ISO Example</title>
<meta charset="iso-8859-1">
</head>
<body>
<p>Bonjour, monde !</p>
</body>
</html>

Make sure your editor does not save the file as windows-1252 if you declare iso-8859-1 in your HTML. For best compatibility, use UTF-8 for both saving and declaring the document encoding.

Learn more:

Related W3C validator issues

Bad value “text/html; charset=windows-1252” for attribute “content” on element “meta”: “charset=” must be followed by “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">

Internal encoding declaration “utf-8” disagrees with the actual encoding of the document (“windows-1252”).

The character encoding declared in the HTML differs from the actual file encoding.

The meta element with charset="utf-8" tells browsers to interpret the document as UTF-8. However, if the file is actually saved in another encoding (such as Windows-1252), validators and browsers will detect a mismatch, leading to this error. To resolve this, you must ensure the file contents and the encoding declaration match.

Recommended: Save your document in UTF-8 encoding to match your meta tag.
Alternatively, if you must use Windows-1252, update charset accordingly.

UTF-8 example (preferred):

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>UTF-8 Encoding Example</title>
    <meta charset="utf-8">
  </head>
  <body>
    <p>This page is encoded in UTF-8.</p>
  </body>
</html>

Windows-1252 example (not recommended):

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Windows-1252 Encoding Example</title>
    <meta charset="windows-1252">
  </head>
  <body>
    <p>This page is encoded in Windows-1252.</p>
  </body>
</html>

Summary:

Use UTF-8 as your file encoding and declare <meta charset="utf-8">.
Always make sure the file is saved using the same encoding you declare in the HTML.

Legacy encoding “windows-1252” used. Documents must use UTF-8.