HTML Validation

The “main” element must not appear as a descendant of the “section” element.

main
section

About This HTML Issue

The main element represents the dominant contents of the document, so it should not be contained within another section.

A document must not have more than one main element that does not have the hidden attribute specified.

A hierarchically correct main element is one whose ancestor elements are limited to html, body, div, form without an accessible name, and autonomous custom elements. Each main element must be a hierarchically correct main element.

Learn more:

Last reviewed: November 29, 2022

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Reading time

1 min read

Category

HTML Validation

Engine

W3C Validator

Last reviewed

November 29, 2022

Resources

Related W3C Validator Issues (10)

A document must not include more than one visible “main” element.

There can only be one visible <main> element in a document. If more are needed (for example for switching between them with JavaScript), only one can be visible, the others should be hidden toggling the hidden attribute.

Example of 2 main elements, where only one is visible:

<main>
  <h1>Active main element</h1>
<!-- content -->

</main>

<main hidden>
  <h1>Hidden main element</h1>
<!-- content -->

</main>

Bad value “article” for attribute “role” on element “section”.

Using role="article" on a <section> element is invalid because article is not a permitted value for the role attribute.

The role attribute in HTML is used to define ARIA roles that describe the purpose of an element for assistive technologies. Only specific, predefined ARIA roles are valid per the WAI-ARIA specification. article is not a recognized ARIA role—use document or other appropriate roles instead, or omit the role attribute entirely. The <article> and <section> elements already have implicit roles, so manual role assignment is rarely necessary or useful for these elements.

Valid uses:

Use <article> without a role attribute for content that is self-contained and intended to be independently distributable or reusable.
Use <section> for grouping related content and omit the role attribute unless a specific ARIA landmark role is needed (such as region).

Example: use <article> for standalone content

<article>
  <h2>News headline</h2>
  <p>News content goes here.</p>
</article>

Example: use <section> without a role attribute for generic grouping

<section>
  <h2>Introduction</h2>
  <p>Section content.</p>
</section>

Bad value “list” for attribute “role” on element “section”.

Use a valid landmark or list role: remove role="list" from the section, or replace the element with a proper list (ul/ol) or a container that supports role="list".

The role attribute must use values allowed by ARIA for the given context. A section element is a landmark and must not be given role="list". If you intend to mark up a list of items, use semantic list elements: ul/ol with li. If you truly need ARIA list semantics (e.g., for custom components), use a neutral container (div) with role="list" and child elements with role="listitem". Prefer native HTML lists over ARIA roles because they provide built-in semantics and better accessibility. Examples:

Native list: use ul + li.
ARIA list (only if native markup isn’t possible): div role="list" containing div role="listitem".

HTML Examples

Example showing the validation error

<section role="list">
  <div>Item A</div>
  <div>Item B</div>
</section>

Fixed using native list semantics (recommended)

<ul>
  <li>Item A</li>
  <li>Item B</li>
</ul>

Fixed using ARIA roles on neutral elements (when custom UI prevents native lists)

<div role="list">
  <div role="listitem">Item A</div>
  <div role="listitem">Item B</div>
</div>

Bad value “section” for attribute “role” on element “section”.

Using role="section" on a <section> element is unnecessary and not recommended.

The <section> element is a semantic HTML5 element that is used to define sections within a document. A <section> inherently carries the semantics of a structural region, so you don’t need to explicitly declare a role attribute for it. The role attribute in HTML is mainly used to enhance accessibility by explicitly defining the purpose of an element when the element’s native HTML semantics are missing or insufficient. However, in this case, since <section> is already semantically meaningful, assigning a role="section" results in redundancy and can cause validation warnings or errors.

HTML5 and ARIA (Accessible Rich Internet Applications) guidelines suggest only using roles when absolutely necessary. Misusing roles can lead to confusion for assistive technologies, potentially impacting user accessibility.

Here’s a correct use of the <section> element without the role attribute:

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Document Title</title>
</head>
<body>
  <header>
    <h1>Website Header</h1>
  </header>
  
  <section>
    <h2>Section Heading</h2>
    <p>This is a paragraph within the section.</p>
  </section>
  
  <footer>
    <p>Website Footer</p>
  </footer>
</body>
</html>

By removing role="section", you leverage the semantic meaning that the <section> element already provides, ensuring cleaner, more accessible, and standards-compliant HTML.

Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.

The <section> element can be used to define sections of a document, like chapters, tabbed content, etc. Consider using a heading element (any of <h2> to </h6>) to present each section. Example:

<h1>All about guitars</h1>
<section>
  <h2>Guitar types</h2>
  <p>Acoustic, electric, classical... we have them all!</p>
</section>
<section>
  <h2>Amplifiers</h2>
  <p>Analog, digital, portable...</p>
</section>

Stray start tag “section”.

The “Stray start tag “section”” error in the W3C HTML Validator typically occurs when a <section> tag appears in an unexpected location within your HTML document structure. This can happen if the <section> tag is not positioned correctly within the HTML5 content model.

Here’s a focused guide to fix this issue:

1. Check the Parent Element

Make sure the <section> tag is placed within elements where it is allowed. According to the HTML5 specification:

A <section> element should be placed within the <body> tag.
It should not be a direct child of an inline element or an element that does not support flow content.

2. Correct Nesting Within Elements

Ensure your HTML structure follows a logical hierarchy and that the <section> element is not incorrectly nested. This example shows a correct usage of the <section> tag:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Correct Usage of Section</title>
</head>
<body>
    <header>
        <h1>Page Title</h1>
    </header>
    
    <nav>
<!-- Navigation links -->

    </nav>
    
    <main>
        <section>
            <h2>Section Title</h2>
            <p>Content for the first section.</p>
        </section>
        
        <section>
            <h2>Another Section Title</h2>
            <p>Content for the second section.</p>
        </section>
    </main>
    
    <footer>
        <p>Footer content</p>
    </footer>
</body>
</html>

3. Check for Mistaken Hierarchy

Verify whether the <section> tag is mistakenly placed inside elements that do not support it, such as directly inside a <p> tag or other inline elements. Correct any incorrect usage. For example this is incorrect usage because the <section> tag is placed after the closing <body> tag:

Incorrect:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Sample page</title>
</head>
<body>
  <h1>Main title</h1>
  <p>Some content</p>
</body>
</html>

<section>
  <h2>Incorrect Section</h2>
  <p>This section should not be after the closing body tag.</p>
</section>

Correct:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Sample page</title>
</head>
<body>
  <h1>Main title</h1>
  <p>Some content</p>

  <section>
    <h2>Correct Section</h2>
    <p>This section is fine.</p>
  </section>
</body>
</html>

Summary

Ensure your <section> tags are used within the <body> tag and other allowed elements.
Maintain a logical hierarchy in your HTML document.
Avoid placing <section> tags inside inline elements like <p>.

Following these steps should resolve the “Stray start tag “section”” error in your HTML document. Validate your HTML again after making these corrections to ensure the issue is resolved.

The “main” element must not appear as a descendant of the “article” element.

main
article

A main element cannot be placed inside an article element according to HTML5 content model rules.

The main element is intended to identify the dominant content of the <body> that is directly related to, or expands upon, the central topic of a document. It is meant to be unique, appearing only once per document, and must not be a descendant of elements like article, aside, header, footer, or nav. Conversely, the article element represents a self-contained composition that could independently be reused or distributed, such as a blog post or news story.

To resolve the error, move the main element so that it is a direct child of the body, and place any article elements inside the main or at the same level, not the other way around.

Incorrect:

<article>
  <main>
    <h1>Article Title</h1>
    <p>This is the article content.</p>
  </main>
</article>

Correct:

<main>
  <article>
    <h1>Article Title</h1>
    <p>This is the article content.</p>
  </article>
</main>

Minimal valid HTML document:

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Article in Main Example</title>
</head>
<body>
  <main>
    <article>
      <h1>Article Title</h1>
      <p>This is the article content.</p>
    </article>
  </main>
</body>
</html>

Use only one main element per page and ensure it is not nested inside sectioning elements such as article.

The “main” element must not appear as a descendant of the “main” element.

main

A main element cannot be nested within another main element.

The main element represents the primary content of a document or application, and there must be only one per page, not placed inside another main. The main element must not be used as a descendant of another main element. This is important for accessibility, semantic correctness, and helps screen readers correctly identify the main content region.

Invalid example (nested main):

<main>
  <h1>Welcome</h1>
  <main>
    <p>This nested main element is invalid.</p>
  </main>
</main>

Valid example (single main only):

<main>
  <h1>Welcome</h1>
  <section>
    <p>This section is valid and can be placed inside main.</p>
  </section>
</main>

If you need to divide the main content, use sectioning elements like section, article, or div inside a single main element, but never nest main inside main.

The “main” role is unnecessary for element “main”.

The main landmark role is used to indicate the primary content of a document. It can be added to an element by using role="main", but instead it’s preferable to just use the <main> element. In that case, it’s unnecessary to make the main role explicit. Examples:

<div role="main">
<!-- this is a valid way to define a main role -->

</div>

<main>
<!-- but this is shorter and uses correct semantic HTML  -->

</main>

The “region” role is unnecessary for element “section”.

A section element automatically defines a landmark region, so adding role="region" is redundant.

According to the HTML specification and WAI-ARIA guidelines, sectioning elements such as section, nav, article, and aside already have implicit landmark roles. Adding an explicit role="region" to a section does not change its semantics, and HTML validators will warn against this unnecessary usage.

Incorrect Example:

<section role="region">
  <h2>Contact Information</h2>
  <p>Email us at info@example.com</p>
</section>

Correct Example:

<section>
  <h2>Contact Information</h2>
  <p>Email us at info@example.com</p>
</section>

If a region of the page does not have an accessible name and you want it to be a landmark, add a heading element (<h1>-<h6>) as the first child to label the region for assistive technologies. Avoid adding redundant ARIA role attributes to native landmark elements for better accessibility and HTML validation.

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