About This HTML Issue
A numeric character reference is pointing to a C1 control code point (U+0080–U+009F), which is disallowed in HTML.
Numeric character references like &#nnn; or &#xhhhh; must resolve to valid Unicode characters.
The C1 control range U+0080–U+009F contains non-characters/control codes, so validators flag them.
Common causes: copying Windows-1252 bytes and encoding them as numeric references (e.g., — for an em dash) or misusing hex values (e.g., ’ for a right single quote).
In HTML, use the proper Unicode character, a valid named character reference, or the correct Unicode code point. Examples: use the actual “—” or — (U+2014), “’” or ’ (U+2019), “€” or € (U+20AC). If you must use numeric references, use the correct code points: — or — for em dash, not —; ’ or ’ for right single quote, not ’.
HTML Examples
Example that reproduces the issue
<!doctype html>
<html lang="en">
<head>
<title>Bad C1 NCR</title>
</head>
<body>
<p>Bad dash: —</p>
<p>Bad quote: ’</p>
</body>
</html>Fixed example
<!doctype html>
<html lang="en">
<head>
<title>Fixed NCRs</title>
</head>
<body>
<p>Good dash: — or — or —</p>
<p>Good quote: ’ or ’ or ’</p>
<p>Euro: € or € or €</p>
</body>
</html>Find issues like this automatically
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