HTML Validation

End tag “code” violates nesting rules.

About This HTML Issue

An end tag </code> has been found violating nesting rules. Check other errors in the same document related to the <code> element, and fix the unallowed nested elements.

Last reviewed: October 27, 2022

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Related W3C Validator Issues (22)

End tag “a” violates nesting rules.

An </a> end tag has been found to violate nesting rules. <a> tags can’t include other <a> tags inside. Most probable cause is an unclosed <a> tag, like in this example:

<a href="one.html">Page 1
<a href="two.html">Page 2</a>

End tag “i” violates nesting rules.

End tag “i” violates nesting rules because the closing  does not match the most recently opened still-unclosed inline element, causing mis-nested tags.

HTML requires elements to be properly nested in a stack-like order: last opened, first closed. Inline elements like the i element (for idiomatic text), em, strong, a, and span must not overlap. When you open i and then open b, you must close b before closing i. Mis-nesting often happens around links or emphasis tags, e.g., i inside a but closed outside. The i element is purely presentational/idiomatic; consider em for emphasis or CSS with font-style: italic;, but whichever you use, keep the nesting consistent.

Common patterns that trigger the error:

Overlapping inline elements: i … b …  … 
Closing order mismatch across a, span, em, strong, i
Copy/paste around icons or screen-reader text

Fix by reordering the tags so they close in reverse order of opening, or by merging styles into one element to avoid overlaps.

HTML Examples

Incorrect (reproduces the validator error)

<p>
  <a href="/about"><i>About <strong>Us</i></strong></a>
</p>

Correct (properly nested)

<p>
  <a href="/about"><i>About <strong>Us</strong></i></a>
</p>

Element “div” not allowed as child of element “ul” in this context. (Suppressing further errors from this subtree.)

Element “X” not allowed as child of element “Y” in this context. (Suppressing further errors from this subtree.)

nesting

End tag “b” violates nesting rules.

nesting
b

An end tag  has been found in an incorrect place within the document, violating nesting rules. A common case is closing it before closing other nested tags, for example:

<!-- This line is incorrect as the <b> tag was closed before the nested <a> tag -->

<b><a href="#">link</b></a>

<!-- This line is OK as every end tag respects the nesting rules -->

<b><a href="#">link</a></b>

End tag “em” violates nesting rules.

nesting
em

An end tag  has been found in an incorrect place within the document, violating nesting rules. A common case is closing it before closing other nested tags, for example:

<!-- This line is incorrect as the <em> tag was closed before the nested <a> tag -->

<em><a href="#">link</em></a>

<!-- This line is OK as every end tag respects the nesting rules -->

<em><a href="#">link</a></em>

End tag for “body” seen, but there were unclosed elements.

body
end tag

End tag had attributes.

End tags in HTML must not have any attributes.

According to the HTML specification, only start tags (also called opening tags) may contain attributes, while end tags must appear as a plain </tagname> with nothing else.

For example, this is invalid and will trigger the error:

<p>Welcome to the site.</p class="welcome">

Correct code removes the attribute from the end tag:

<p>Welcome to the site.</p>

If you need the element to have an attribute, only include it in the start tag:

<p class="welcome">Welcome to the site.</p>

End tag “strong” violates nesting rules.

An end tag  has been found in an incorrect place within the document, violating nesting rules. A common case is closing it before closing other nested tags, for example:

<!-- This line is incorrect as the <strong> tag was closed before the nested <a> tag -->

<strong><a href="#">link</strong></a>

<!-- This line is OK as every end tag respects the nesting rules -->

<strong><a href="#">link</a></strong>

End tag X did not match the name of the current open element Y.

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