About This HTML Issue
HTML documents must use UTF-8 as their character encoding. The legacy encoding iso-8859-15 is no longer allowed in modern HTML.
The HTML living standard requires all documents to be encoded in UTF-8. Older encodings like iso-8859-15 (also known as Latin-9) were common in the past, especially for Western European languages, but they are now considered legacy. UTF-8 supports virtually all characters from every writing system, making it the universal standard for the web.
To fix this, you need to do two things. First, update the <meta> charset declaration in your HTML to specify UTF-8. Second — and this is the important part — you must actually save or convert the file itself to UTF-8 encoding. Simply changing the meta tag without re-encoding the file can cause characters like é, ñ, or € to display incorrectly.
Most modern code editors (VS Code, Sublime Text, Notepad++) let you change the file encoding. In VS Code, click the encoding label in the bottom status bar and choose “Save with Encoding” → “UTF-8”.
If your server is sending an iso-8859-15 charset in the HTTP Content-Type header, you’ll also need to update that. The HTTP header takes precedence over the meta tag.
HTML Examples
❌ Incorrect: legacy encoding
<!DOCTYPE html>
<html lang="fr">
<head>
<meta charset="iso-8859-15">
<title>Mon site</title>
</head>
<body>
<p>Bienvenue sur mon site € 2025</p>
</body>
</html>✅ Correct: UTF-8 encoding
<!DOCTYPE html>
<html lang="fr">
<head>
<meta charset="utf-8">
<title>Mon site</title>
</head>
<body>
<p>Bienvenue sur mon site € 2025</p>
</body>
</html>
If you’re using an Apache server, update your .htaccess or server config:
AddDefaultCharset UTF-8For Nginx, update the server block:
charset utf-8;Find issues like this automatically
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