Validación HTML: Character reference was not terminated by a semicolon.

Acerca de este problema HTML

Character references are how HTML represents special characters that would otherwise be interpreted as markup or that aren’t easily typed on a keyboard. They come in three forms:

Named references like &, <, ©
Decimal numeric references like <, ©
Hexadecimal numeric references like <, ©

All three forms share the same structure: they begin with & and must end with ;. When you omit the trailing semicolon, the HTML parser enters error recovery mode. Depending on the context, it may still resolve the reference (browsers are lenient), but this behavior is not guaranteed and varies across situations. For example, &copy without a semicolon might still render as ©, but &notit could be misinterpreted as the ¬ (¬) reference followed by it, producing unexpected output like “¬it” instead of the literal text “&notit”.

Why this matters

Unpredictable rendering: Without the semicolon, browsers use heuristic error recovery that can produce different results depending on surrounding text. What looks fine today might break with different adjacent characters.
Standards compliance: The WHATWG HTML specification requires the semicolon terminator. Omitting it is a parse error.
Maintainability: Other developers (or future you) may not realize the ampersand was intended as a character reference, making the code harder to read and maintain.
Data integrity: In URLs within href attributes, a missing semicolon on a character reference can corrupt query parameters and produce broken links.

How to fix it

Add the missing semicolon to the end of every character reference.
If you meant a literal ampersand, use & instead of a bare &. This is especially common in URLs with query strings.
Search your document for patterns like &something without a trailing ; to catch all instances.

Examples

❌ Missing semicolon on named references

<p>5 &lt 10 and 10 &gt 5</p>
<p>&copy 2024 All rights reserved</p>

✅ Properly terminated named references

<p>5 &lt; 10 and 10 &gt; 5</p>
<p>&copy; 2024 All rights reserved</p>

❌ Missing semicolon on numeric references

<p>The letter A: &#65</p>
<p>Hex example: &#x41</p>

✅ Properly terminated numeric references

<p>The letter A: &#65;</p>
<p>Hex example: &#x41;</p>

❌ Bare ampersand in a URL (common mistake)

<a href="https://example.com/search?name=alice&age=30">Search</a>

Here the validator sees &age and tries to interpret it as a character reference without a semicolon.

✅ Escaped ampersand in a URL

<a href="https://example.com/search?name=alice&amp;age=30">Search</a>

❌ Ambiguous reference causing wrong output

<p>The entity &notit; doesn't exist, but &not without a semicolon resolves to ¬</p>

✅ Use `&` when you want a literal ampersand

<p>The text &amp;notit is displayed literally when properly escaped.</p>

A quick rule of thumb: every & in your HTML should either be the start of a complete, semicolon-terminated character reference, or it should itself be written as &.