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Reference > WCAG21 Level A

Issues due to failing to meet the WCAG21 Level A and US Section 508 accessibility guidelines

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[WCAG21 1.1.1 (A)] When using images, specify a short text alternative
If there is no alternative text, then assistive technologies are not able to identify the image or to convey its purpose to the user. So, add an 'alt', 'aria-label' or 'aria-labelledby' attribute as appropriate. See WCAG 2.1 Failure F65.
[WCAG21 1.1.1 (A)] When using the <area> element, specify a short text alternative with the 'alt' attribute
Ensure the <area> element 'alt' attribute value is displayed in response to attaining focus (including keyboard focus), and that this applies when images are loaded and not loaded. See WCAG 2.1 HTML Technique H24.
[WCAG21 1.1.1 (A)] When using a text alternative, it must be meaningful
If the text in the 'text alternative' cannot be used in place of the non-text content without losing information or function then it fails because it is not, in fact, an alternative to the non-text content. See WCAG 2.1 Failure F30.
[WCAG21 1.1.1 (A)] When using a text alternative, it must be meaningful
If the text in the 'text alternative' cannot be used in place of the non-text content without losing information or function then it fails because it is not, in fact, an alternative to the non-text content. See WCAG 2.1 Failure F30.
[WCAG21 1.1.1 (A)] The 'title', 'aria-label' and 'aria-labelledby' attributes should be missing or empty
When using <img>, it is valid to have an empty 'alt' attribute for images that have no content, but the 'title', 'aria-label' and 'aria-labelledby' attributes should be missing or empty as well. See WCAG 2.1 HTML Technique H67.
[WCAG21 1.1.1 (A)] Applets should have a text alternative in an 'alt' attribute and in the body text
When using <applet>, you should provide an 'alt' attribute with a non-blank value and provide a text alternative in the body text of the applet. See WCAG 2.1 HTML Technique H35.
[WCAG21 1.1.1 (A)] Objects should have a text alternative
When using <object>, you should provide a text alternative in the body text of the object. See WCAG 2.1 HTML Technique H53.
[WCAG21 1.1.1 (A)] Do not use the 'alt' attribute here
Although HTML may allow the 'alt' attribute here, it should only be used on image submit buttons. User agent support for this attribute on other types of form controls is not well defined. Other mechanisms are available to label these controls. See WCAG 2.1 HTML Technique H36.
[WCAG21 1.1.1 (A)] Use 'alt' text for short descriptions
The 'alt' text you specified was at least 100 characters long. For long descriptions you should use the 'aria-describedby' attribute, a separate descriptive link, or image map. See WCAG 2.1 HTML Technique H45.
[WCAG21 1.1.1 (A)] Use an 'aria-label' to provide an accessible name
The button label used may not indicate the intended use for unsighted users. Use an 'aria-label' to make its purpose clear. See WCAG 2.1 ARIA Technique ARIA14.
[WCAG21 1.1.1 (A)] When using a text alternative, it must not include ASCII art or smileys
If the text in the 'text alternative' when read aloud does not sound meaningful then it fails because it is not, in fact, an alternative to the non-text content. See WCAG 2.1 Failure F72.
[WCAG21 1.1.1 (A)] Embedded objects should have a text alternative
When using <embed>, specify a short text equivalent with the 'alt', 'aria-label' or 'aria-labelledby' attribute. See WCAG 2.1 Guideline 1.1 Text Alternatives.
[WCAG21 1.1.1 (A)] Is the 'alt' text deliberately empty?
When using <img>, it is valid to have an empty 'alt' attribute for images that have no content; such as spacers and parts of larger images that have been broken up or used for other layout purposes. You may wish to check that in this case the 'alt' text has not simply been forgotten. See WCAG 2.1 Failure F30.
[WCAG21 1.1.1 (A)] When using images, specify a short text alternative with the 'alt' attribute
If there is no 'alt' attribute, then assistive technologies are not able to identify the image or to convey its purpose to the user. This is only a warning and not an error because of the presence of the 'generator-unable-to-provide-required-alt' attribute. See WCAG 2.1 Failure F65.
[WCAG21 1.1.1 (A)] Use 'alt' text for short descriptions
The 'alt' text you specified was at least 75 characters long. For long descriptions you should use the 'aria-describedby' attribute, a separate descriptive link, or image map. See WCAG 2.1 HTML Technique H45.
[WCAG21 1.1.1 (A)] The corresponding <noembed> element is missing or misplaced
For each <embed> element you should provide either a nested <noembed> element or a <noembed> element immediately following it. See WCAG 2.1 HTML Technique H46.
[WCAG21 1.1.1 (A) Is the 'aria-labelledby' or 'aria-label' text deliberately empty?
The 'aria-labelledby' and 'aria-label' attributes are used to provide a label for objects that can be read by assistive technology, but it has been found to be empty. You may wish to check that the text has not simply been forgotten. See WCAG 2.1 ARIA Technique ARIA6.
[WCAG21 1.1.1 (A)] Duplication of alternative text
Two nearby images with the same alternative text, often indicates redundancy. Consider removing the alternative text from one of them, especially if they are grouped together. See WCAG 2.1 General Technique G196.
[WCAG21 1.1.1/1.3.1/3.3.2/4.1.2 (A)] User interface controls without a label should have an accessible name
Use the 'aria-label', 'aria-labelledby', or where appropriate 'value', attributes to label form controls when the visual design cannot accommodate the label (for example, if there is no text on the screen that can be identified as a label) or where it might be confusing or not possible to use a label. User agents, including assisting technology, can use these attributes. See WCAG 2.1 Failure F68.
[WCAG21 1.1.1/1.3.1/3.3.2/4.1.2 (A)] User interface controls should have a label or an accessible name
Associate form controls with <label> tags, or use the 'aria-label' or 'aria-labelledby' attributes to label controls where it might be confusing or not possible to use a label. See WCAG 2.1 Failure F68.
[WCAG21 1.1.1/2.4.4 (A)] Link text is missing
Describe the purpose of a link by providing descriptive text as the content of the element, or provide an 'aria-label' or 'aria-labelledby' attribute. The description lets a user distinguish this link from other links in the Web page and helps the user determine whether to follow the link. The URL of the destination is generally not sufficiently descriptive. See WCAG 2.1 HTML Technique H30.
[WCAG21 1.1.1/2.4.4 (A)] Do not use the URL as link text
Describe the purpose of a link by providing descriptive text as the content of the <a> element, or provide an 'aria-label' or 'aria-labelledby' attribute. The description lets a user distinguish this link from other links in the Web page and helps the user determine whether to follow the link. The URL of the destination is generally not sufficiently descriptive. See WCAG 2.1 HTML Technique H30.
[WCAG21 1.1.1/4.1.2 (A)] Do not use images as frame targets, always point to web pages
Rather than point directly to an image, embed the image in a web page so that if the content of the frame is changed the text-alternative can follow this change. See WCAG 2.1 Failure F20.
[WCAG21 1.2.1 (A)] Add a text alternative to describe the audio/visual media
Provide a text alternative to describe the audio/visual media that is being linked to or played by using text within this element, or a 'aria-label' or 'aria-labelledby' attribute. See Understanding 1.2.1.
[WCAG21 1.2.1 (A)] Add a parent <video> element to provide better accessibility
The HTML5 <video> element provides better support for captions and text transcripts. So, either replace this element with <video>, or wrap it within <video> if you still need to support legacy browsers.
[WCAG21 1.2.1 (A)] Add a parent <audio> element to provide better accessibility
The HTML5 <audio> element provides better support for text transcripts. So, either replace this element with <audio>, or wrap it within <audio> if you still need to support legacy browsers.
[WCAG21 1.2.1 (A)] Ensure there is a text description of this audio
Text can be made accessible to everyone. So, unless this is a media alternative for text (and is clearly labelled as such), provide a text description or transcript. This may be done by adding a link to the description (immediately following this), or by adding an 'aria-describedby' attribute. See Understanding 1.2.1.
[WCAG21 1.2.2 (A)] Where possible ensure that captions for video are provided and accessible
If there is a caption track for the video then use the <track> element to refer to it. See Understanding 1.2.2.
[WCAG21 1.2.2 (A)] Where possible ensure that captions for video are provided and accessible
f there is a caption track for the video then ensure that the video player can display them and they are in sync with the video. See Understanding 1.2.2.
[WCAG21 1.2.3 (A)] Ensure there is a text description of this video
Text can be made accessible to everyone. So, unless this is a media alternative for text (and is clearly labelled as such), provide a text description or transcript. This may be done by adding a link to the description (immediately following this), or by adding an 'aria-describedby' attribute, or with the <video> element. If a descriptive track exists, you can refer to it using the <track> element. See Understanding 1.2.3.
[WCAG21 1.3.1 (A)] The 'summary' and 'caption' are the same
Making the 'caption' and 'summary' the same is unnecessarily confusing. See WCAG 2.1 HTML Technique H39.
[WCAG21 1.3.1 (A)] The accessible name and description must be different
The name is used to identify and/or provide a summary, the description describes the table in more detail. See Accessibility API Mappings: Table Element, and Understanding 1.3.1.
[WCAG21 1.3.1 (A)] Invalid value for 'scope' attribute
The 'scope' attribute must have one of the following values: row, col, rowgroup, or colgroup. See WCAG 2.1 HTML Technique H63.
[WCAG21 1.3.1 (A)] Unique accessible name required. See matching tag on line: LINE_NUMBER
Data tables must have unique accessible names to help identify them and to differentiate between each table on the page. The accessible name is provided by 'aria-labelledby' > 'aria-label' > caption > 'title' > 'summary'. If two tables contain the same information then number them in the accessible name. See Understanding 1.3.1.
[WCAG21 1.3.1 (A)] For complex data tables explicitly associate data cells and header cells
For complex data tables you must use markup to explicitly associate data cells and header cells, and no such markup was found. See WCAG 2.1 Failure F91.
[WCAG21 1.3.1 (A)] Nest headings properly (H1 > H2 > H3)
Heading elements must be ordered properly. For example, H2 elements should follow H1 elements, H3 elements should follow H2 elements, etc. Developers should not skip levels or use headings for presentation effects. See WCAG 2.1 Failure F43.
[WCAG21 1.3.1 (A)] Label text is missing
Associate labels properly with their controls. See WCAG 2.1 Failure F68.
[WCAG21 1.3.1 (A)] Associate labels with just one form control
Associate labels properly with their controls. See WCAG 2.1 Failure F68.
[WCAG21 1.3.1 (A)] Only associate labels with specific form controls
Associate labels properly with their controls. See WCAG 2.1 Failure F68.
[WCAG21 1.3.1 (A)] Layout tables cannot have data table elements and/or attributes
The role attribute has been used to mark a layout table, but this table contains elements and/or attributes that must only be used with data tables. Layout tables must not have any description and can only contain <tr> and <td> elements. See WCAG 2.1 Failure F46.
[WCAG21 1.3.1 (A)] Use CSS for presentation effects, use <em> or <strong> for emphasis
Tags that are being used purely to create a visual presentation effect should not be used. You should use CSS to control layout and presentation so that users and their aids may control it. See WCAG 2.1 General Technique G140.
[WCAG21 1.3.1 (A)] Reference to a missing or incorrect 'id' attribute
References to other parts of the same document must exist to ensure that Web pages can be interpreted properly. Note that certain attributes such as 'for' can only reference certain elements in the same <form>. See Understanding 1.3.1.
[WCAG21 1.3.1 (A)] Heading with no content
Ensure that all headings contain informative content. This is necessary because users may navigate or search by headings. See Understanding 1.3.1.
[WCAG21 1.3.1 (A)] The value of the attribute must match an 'id' in the same document
Each of the ids listed for this aria attribute must match elements elsewhere in the document. See ARIA 1.2.
[WCAG21 1.3.1 (A)] Elements with the 'ROLE' role must be owned by an element with one of these roles: LIST OF ROLES
The ARIA specification requires that elements with certain roles must be contained within or owned by elements with other roles. So you need to add one of the roles listed to an owning element. See ARIA 1.2.
[WCAG21 1.3.1 (A)] Elements with the 'ROLE' role must own an element with one of these roles: LIST OF ROLES
The ARIA specification requires that elements with certain roles must contain or own elements with other roles. So you need to add one of the roles listed to an owned element. See ARIA 1.2.
[WCAG21 1.3.1 (A)] Do not insert content using CSS
Content inserted using CSS may not appear when CSS is turned off, or the user is using their own accessible style sheet. See WCAG 2.1 Failure F87.
[WCAG21 1.3.1 (A)] Use semantic markup to convey information
Information conveyed using CSS will be misunderstood by accessibility aids. For example, you should use <strong> in place of 'font-weight:bold' on <span>. See WCAG 2.1 Failure F2.
[WCAG21 1.3.1 (A)] Distinguish between navigation groups using an ARIA label
When the <nav> element is employed more than once on a page, distinguish between the navigation groups by using an 'aria-label' or 'aria-labelledby' attribute. See WCAG 2.1 HTML Technique H97.
[WCAG21 1.3.1 (A)] Heading markup should be used if this is a heading
This paragraph of text is all bold/strong or all italic/em text and so will look like a heading on screen. Use heading markup if that is the intention, so that accessibility aids will recognise it as such. See WCAG 2.1 HTML Technique H42.
[WCAG21 1.3.1 (A)] Using <pre> is often a bad idea
Using <pre> implies the content has structure, which screen readers may not be able to convey. If the structure is important then consider using other markup that screen readers can properly interpret such as lists or tables, or provide alternative text to inform users about the structure. See Understanding 1.3.1.
[WCAG21 1.3.1 (A)] Provide an accessible description for complex data tables
Use 'aria-describedby', <caption>, 'title' or 'summary' attributes to describe the table. This must be a full description and not a short one. If you see this warning even though you have provided a <caption>, 'title' or 'summary', then this has most likely already been used to provide the accessible name. See Accessibility API Mappings: Table Element, and Understanding 1.3.1.
[WCAG21 1.3.1/3.3.2 (A)] The <fieldset> element should only be used within a form
Using a <fieldset> outside of a form usually indicates it is being used for presentation effects. See WCAG 2.1 HTML Technique H71.
[WCAG21 1.3.1/3.3.2 (A)] The <fieldset> element should be used to group radio buttons and checkboxes
Because groups of radio buttons and checkboxes are multiple controls, it is particularly important that they be grouped semantically so they can be more easily treated as a single control. See WCAG 2.1 HTML Technique H71.
[WCAG21 1.3.1/3.3.2 (A)] Each <fieldset> should have a <legend> element that includes a description of that group
The first element inside the <fieldset> should be a <legend>, which provides a label or instructions for the group. See WCAG 2.1 HTML Technique H71.
[WCAG21 1.3.1/4.1.1 (A)] Duplicate 'accesskey' value. See matching tag(s) on line(s): LINE_NUMBERS
Access keys must have unique values to be useful. See WCAG 2.1 Failure F77.
[WCAG21 1.3.1/4.1.1 (A)] Missing 'id' attribute corresponding to the 'axis' attribute
If you specify an 'axis' attribute you must also specify an 'id' attribute and this 'id' attribute must also exist in at least one 'headers' attribute in another table cell. See WCAG 2.1 Failure F77.
[WCAG21 1.3.2 (A)] Nested tables are difficult to for screen readers to read
Screen readers can struggle to read out tables sensibly, and nesting them makes them almost impossible to understand when read out. Either combine the tables into one, or use alternative markup to represent them. See WCAG 2.1 Failure F49.
[WCAG21 1.3.2 (A)] Layout tables must represent their content in a meaningful sequence
Screen readers can struggle to read out tables sensibly, so it is often better to use alternative markup and CSS to layout content. Try disabling the table markup to see if it still makes sense. See WCAG 2.1 Failure F49.
[WCAG21 1.4.2 (A)] Audio that auto-plays must have a means to stop it
Media content with audio that automatically starts playing when the page loads must provide a means for the user able to stop, pause or mute it. If the audio lasts more than 3 seconds and there is no other way of stopping it you should add the 'controls' attribute. See WCAG 2.1 Failure F93.
[WCAG21 2.1.1 (A)] Server-side image maps are not keyboard accessible
Server-side image maps are not keyboard accessible. Consider an accessible alternative instead. See Understanding 2.1.1.
[WCAG21 2.1.1 (A)] <a> or <area> without an 'href' cannot receive keyboard focus
If there is no link then there must be no alternative text provided. So, remove any 'alt', 'title', 'aria-label' or 'aria-labelledby' attributes. See WCAG 2.1 Success Criterion 2.1.1.
[WCAG21 2.1.1 (A)] Non-interactive element with onkey* attribute
You must add a 'tabindex' attribute to non-interactive elements that have onkey* event handlers to make them focusable. Otherwise users will not be able to tab to it to be able to fire the onkey* event. See WCAG 2.1 Success Criterion 2.1.1.
[WCAG21 2.1.1 (A)] Mouse/Pointer event handlers require keyboard equivalents
When using mouse/pointer event handlers on elements that can be accessed by keyboard, ensure that you provide an equivalent keyboard handler. See WCAG 2.1 Failure F54.
[WCAG21 2.1.1/2.1.2 (A)] Ensure that there is keyboard support and no trap for interactive elements
All interactive items on a page must provide keyboard support so they can be used without a mouse. In addition, you should be able to use the keyboard to exit the item to the web page the item is embedded in, so the user does not become trapped in it. A common way of avoiding traps is to add 'tabindex=-1' to the element so users cannot accidentally tab into it. See WCAG 2.1 Success Criterion 2.1.
[WCAG21 2.1.1/3.2.1 (A)] Do not remove focus when focus is received
The system focus indicator is an important part of accessibility for keyboard users. Removing focus entirely means the content can only be accessed by a pointer device. See WCAG 2.1 Failure F55.
[WCAG21 2.2.1 (A)] You should not use a non-zero page refresh or redirect
It is important that the time-out is set to zero, to avoid that content is displayed before the new page is loaded. See WCAG 2.1 Failure F41.
[WCAG21 2.2.1 (A)] You should not use HTTP Refresh headers
It is important that the time-out is set to zero, to avoid content being displayed before the new page is loaded. See WCAG 2.1 Failure F40.
[WCAG21 2.2.1 (A)] You should not use a non-zero page redirect
Pages that automatically refresh can upset screen readers and disorient sighted users. See WCAG 2.1 Failure F58.
[WCAG21 2.2.2 (A)] Do not use this tag. Consider <em> or using CSS instead
Using blink causes any text inside the element to blink at a predetermined rate, which cannot be interrupted by the user or disabled. See WCAG 2.1 Failure F47.
[WCAG21 2.2.2 (A)] Do not use this tag. Consider an alternative instead
With the <marquee> element there is moving or scrolling content that cannot be paused and resumed by users. Some users with low vision or cognitive disabilities will not be able to perceive the content. See WCAG 2.1 Failure F16.
[WCAG21 2.2.2 (A)] Do not use 'blink'
Using 'blink' can cause a severe distraction for users. See WCAG 2.1 Failure F4.
[WCAG21 2.2.2 (A)] Videos that auto-play must have a means to stop them
Media content with video that automatically starts playing when the page loads must provide a means for the user able to stop, or pause it. If the video lasts more than 5 seconds and there is no other way of stopping it you should add the 'controls' attribute. See Understanding 2.2.2.
[WCAG21 2.4.1 (A)] Use heading elements to convey structure
Many assistive technologies provide navigation using headings, including skipping navigational links. If your document has any structure you should use heading markup to convey the structure of the content. Even a single header will make it easier for users. See WCAG 2.1 HTML Technique H69.
[WCAG21 2.4.1 (A)] Skip navigation links should be the first link on a page
A skip navigation link was detected but it was not the first link on the page. Unless it is the first link then it may defeat the point for users. See Understanding 2.4.1, and Skip Navigation.
[WCAG21 2.4.1 (A)] Skip navigation links should not be hidden within images
Hidden skip navigation links may not be accessible. You should consider replacing this with a visible link and using CSS to hide it until the tab key is used. See Understanding 2.4.1, and Skip Navigation.
[WCAG21 2.4.1 (A)] Add a skip navigation link as the first link on the page
If your document has structure then you should add a skip navigation link to make it easier for accessible users to get to the page's content. To ensure detection, skip navigation links should point to a <main> element, or an element with role='main'. See Understanding 2.4.1, and Skip Navigation.
[WCAG21 2.4.1/4.1.2 (A)] Add a 'title' attribute to facilitate identification and navigation
Title each <frame> and <iframe> to facilitate identification and navigation. See WCAG 2.1 HTML Technique H64.
[WCAG21 2.4.2 (A)] Add a <title> tag to the page to describe it
You should always provide a <title> element in the head section that defines in a simple phrase the purpose of the document. See WCAG 2.1 Failure F25.
[WCAG21 2.4.2 (A)] Add a concise, meaningful <title> tag to the page to describe it
The <title> should contain a concise, meaningful description, less than 150 characters long. See WCAG 2.1 Failure F25.
[WCAG21 2.4.3 (A)] When 'tabindex' is used the tab order may become incorrect
When using 'tabindex', changes to the page can easily change the tab order such that it no longer follows logical relationships and sequences in the content. So, you should manually check any pages that use 'tabindex' to be sure they still make sense. See WCAG 2.1 Failure F44.
[WCAG21 2.4.4 (A)] Unnecessary duplication of link text. See matching tag on line: LINE_NUMBER
A 'stuttering' effect occurs when you have two adjacent links with the same link text. Consider combining the links into one and removing any redundant link text. See WCAG 2.1 HTML Technique H2.
[WCAG21 2.4.4 (A)] Unnecessary duplication of link text. See matching tag on line: LINE_NUMBER
A 'stuttering' effect occurs when you have attributes or 'alt' text of images within the link with the same link text. Consider removing the 'alt' text of the image where the link text already provides the context for the image. See WCAG 2.1 HTML Technique H2.
[WCAG21 2.4.4 (A)] Is the 'title' text deliberately empty?
The 'title' attribute is used to provide additional information to help clarify or further describe the purpose of a link, but it has been found to be empty. You may wish to check that the title text has not simply been forgotten. See WCAG 2.1 HTML Technique H33.
[WCAG21 2.4.4 (A)] Identical adjacent links that use different link text may be confusing. See matching tag on line: LINE_NUMBER
If you have adjacent links to the same place with different link text it can be confusing to the user. You should consider combining these into one link and removing any redundant link text. See Understanding 2.4.4.
[WCAG21 2.4.4 (A)] Different adjacent links that use the same link text may be confusing. See matching tag on line: LINE_NUMBER
If you have adjacent links to different places, but with the same link text it can be confusing to the user. So, you should either change the link text or add a unique 'aria-label' or 'aria-labelledby' attribute to each link. See Understanding 2.4.4.
[WCAG21 2.5.3 (A)] The accessible name must contain the visible label text
The accessible name used by accessibility aids must contain the text displayed by the visible label. See Understanding 2.5.3 and Accessibility API Mappings.
[WCAG21 3.1.1 (A)] The 'lang' or 'xml:lang' attribute does not have a valid value
The attribute contains an unrecognised, or malformed language code. See Tags for Identifying Languages, and WCAG 2.1 HTML Technique H57.
[WCAG21 3.1.1 (A)] Use the 'lang' attribute to denote the primary language of the document
You should always identify the primary natural language of a document using a 'lang' attribute on the <html> element. See WCAG 2.1 HTML Technique H57.
[WCAG21 3.1.1 (A)] The 'xml:lang' and 'lang' attributes should have the same value
When 'xml:lang' and 'lang' attributes appear in the same element they should have the same value. See WCAG 2.1 HTML Technique H57.
[WCAG21 3.2.2 (A)] The submit button is missing
You must provide a mechanism that allows users to explicitly request changes of context. The intended use of a submit button is to generate an HTTP request that submits data entered in a form, so it is an appropriate control to use for causing a change of context. See WCAG 2.1 HTML Technique H32.
[WCAG21 3.2.2 (A)] Automatically submitting forms prevents keyboard operation
Using 'onchange' to automatically submit forms prevents keyboard operation by unexpectedly changing the context. See WCAG 2.1 Failure F36.
[WCAG21 3.2.2 (A)] Using 'onchange' with selections may prevent keyboard operation
Using 'onchange' with selections may prevent keyboard operation, because the handler fires as the selection is changed using the keyboard, which may move the focus or change the context. See Understanding 3.2.2.
[WCAG21 3.2.2 (A)] A submit button is missing
You must provide a mechanism that allows users to explicitly request changes of context. The intended use of a submit button is to generate an HTTP request that submits data entered in a form, so it is an appropriate control to use for causing a change of context. See WCAG 2.1 HTML Technique H32.
[WCAG21 3.3.2 (A)] The matching <label> text must appear before/after the control
Associate labels properly with their controls. See WCAG 2.1 HTML Technique H44.
[WCAG21 4.1.1 (A)] Duplicate 'id' value found. See matching tag(s) on line(s): LINE_NUMBERS
IDs must be unique within a document to ensure that Web pages can be interpreted consistently. See WCAG 2.1 Failure F77.
[WCAG21 4.1.1 (A)] This tag or content is not allowed here. One of the following was expected: LIST OF VALID TYPES/TAGS
When using ARIA roles there are additional rules for what HTML elements can be nested within others. See ARIA in HTML.
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[WCAG21 4.1.1 (A)] Interactive elements are not allowed here
When using ARIA roles there are additional rules for what HTML elements can be nested within others. See ARIA in HTML.
[WCAG21 4.1.1/4.1.2 (A)] No HTML validation was selected
You should always select a HTML Validation to ensure that the page does not have any issues which may prevent accessibility aids from properly representing the page. See WCAG 2.1 HTML Technique H88.
[WCAG21 4.1.2 (A)] This role must have an accessible name
Some ARIA roles are required to have an accessible name to allow accessibility aids to interact properly with them. Use 'aria-labelledby' if a visible label is present, otherwise use 'aria-label' to provide this. See Accessible Name Guidance by Role.
[WCAG21 4.1.2 (A)] This role must have an accessible name
Some ARIA roles are required to have an accessible name to allow accessibility aids to interact properly with them. Ideally use visible, descendant content to provide this. Failing that use 'aria-labelledby' if a visible label is present, otherwise use 'aria-label'. See Accessible Name Guidance by Role.
[WCAG21 4.1.2 (A)] This role must not have an accessible name
Some ARIA roles must not have an accessible name as it may confuse some accessibility aids. You should remove any 'aria-labelledby' or 'aria-label' attributes. See Accessible Name Guidance by Role.
[WCAG21 4.1.2 (A)] User interface components must have an accessible name
User interface components are required to have an accessible name to allow users interact properly with them when using accessibility aids. Use 'aria-labelledby' if a visible label is present, otherwise use 'aria-label' to provide this. See Understanding 4.1.2.
[WCAG21 4.1.2 (A)] ARIA attributes such as 'role' and 'aria-...' are not valid here
Some elements (sometimes combined with certain attributes) cannot have ARIA attributes specified. See ARIA in HTML.
[WCAG21 4.1.2 (A)] The value of the 'role' attribute is not valid for this element
Elements can only have specific roles as defined by the ARIA specification. So, you may be better off using a more appropriate element for this role. See ARIA in HTML.
[WCAG21 4.1.2 (A)] The 'ATTRIBUTE NAME' attribute for this ARIA role is missing
The ARIA specification requires that the attribute indicated should be used with the specified role(s). See ARIA 1.2.
[WCAG21 4.1.2 (A)] The 'ATTRIBUTE NAME' attribute is not allowed in this context
The ARIA specification only allows certain 'aria-...' attributes to be used with certain roles. See ARIA 1.2.
[WCAG21 4.1.2 (A)] Do not use role=presentation|none or aria-hidden=true on a focusable element
Using either of these on a sequentially focusable element will result in some users focusing on 'nothing'. A sequentially focusable element is an interactive element, or one with a positive 'tabindex'. See Fourth Rule of ARIA Use.
[WCAG21 4.1.2 (A)] Do not mix role=presentation|none and global ARIA attributes
When global ARIA attributes are present using 'role=presentation|none' has no effect. You should either remove all the aria-* attributes or change or remove the 'role'. See Conditions that cause 'presentation' to be ignored.
[WCAG21 4.1.2 (A)] The 'ATTRIBUTE NAME' attribute is not allowed here
The ARIA specification only allows certain 'aria-...' attributes. See ARIA 1.2.
[WCAG21 4.1.2 (A)] The 'ATTRIBUTE NAME' attribute does not have a valid value: LIST OF VALID VALUES
The ARIA specification allows 'aria-...' attributes to only have certain values. Usually a list of valid values will be displayed when you see this message. See ARIA 1.2.
[WCAG21 4.1.2 (A)] You must not use ARIA attributes which conflict with equivalent regular attributes
Web developers must not use an aria-* attribute when it conflicts with an equivalent regular attribute for an element. See ARIA in HTML.
[WCAG21 4.1.2 (A)] Avoid using accessible names created from fallback attributes
An accessible name generated from 'title', 'placeholder' or default values for <input> buttons, typically yields a low quality accessible name. Instead use the recommended way of setting the accessible name for this element. See Avoid Fallback, and Accessible Name Computation.
[WCAG21 4.1.2 (A)] You should not use ARIA roles, that are the default for the element
Web developers should not set the ARIA role and aria-* attributes to values that match the default implicit ARIA semantics. See ARIA in HTML.
[WCAG21 4.1.2 (A)] You should not use ARIA attributes in place of equivalent regular attributes
Web developers should not use aria-* attributes when there is an equivalent regular attribute for an element. See ARIA in HTML.
[WCAG21 4.1.2 (A)] The ARIA_FEATURE has been deprecated
Deprecated features could be removed at any time, so you should not rely on them. The ARIA specification will usually provide an alternative or state why it should not be used at all. See ARIA 1.2.

Reference > WCAG21 Level AA

Issues due to failing to meet the WCAG21 Level AA and US Section 508 accessibility guidelines

Code
Summary
Details
[WCAG21 1.3.5 (AA)] The 'autocomplete' attribute is incorrect
The 'autocomplete' attribute is a very important aid, and so must always be used correctly. There are strict rules as to what values it can have, and these vary depending on the context it is used in. See WCAG 2.1 Failure F107.
[WCAG21 1.4.3 (AA)] Large text within this element has a low contrast ratio. Detected ratio: RATIO
Ensure that the visual presentation of large text has a contrast ratio of at least 3:1, so that's it's easy to read. Note that our contrast ratio calculation does not account for background images, gradients or text shadows. See WCAG 2.1 Success Criterion 1.4.3.
[WCAG21 1.4.3 (AA)] Text within this element has a low contrast ratio. Detected ratio: RATIO
Ensure that the visual presentation of text has a contrast ratio of at least 4.5:1, so that's it's easy to read. Note that our contrast ratio calculation does not account for background images, gradients or text shadows. See WCAG 2.1 Success Criterion 1.4.3.
[WCAG21 1.4.4 (AA)] Use relative rather than absolute units
Using relative units helps the page to be rendered correctly at different resolutions and allows people with sight difficulties to 'zoom in' to pages to read them. See Understanding 1.4.4.
[WCAG21 1.4.4 (AA)] Do not use 'viewport' settings which prevent the user from zooming in
Using 'user-scalable=no' or 'maximum-scale' with a value less than 2.0 may prevent people with sight difficulties from being able to 'zoom in' to pages to read them. See Understanding 1.4.4.
[WCAG21 1.4.12 (AA)] Do not use !important with letter-spacing, word-spacing or line-height in style attributes
Accessibility aids may not be able to override this when it is used in a style attribute with !important set. This may mean that users are not be able to read the text. See WCAG 2.1 Success Criterion 1.4.12.
[WCAG21 1.4.12 (AA)] Do not use !important with letter-spacing, word-spacing or line-height in style attributes
Accessibility aids may not be able to override this when it is used in a style attribute with !important set. This may mean that users are not be able to read the text. See WCAG 2.1 Success Criterion 1.4.12.
[WCAG21 2.4.5 (AA)] Ensure there is more than one way to locate each web page
Ensure that there is more than one way to navigate to each page on the website. This is commonly achieved by adding a link to a site map, or a search facility, to each page. See WCAG 2.1 Success Criterion 2.4.5.
E879
[WCAG21 2.4.6 (AA)] Unique accessible name required. See matching tag on line: LINE_NUMBER
Data tables must have unique accessible names to help identify them and to differentiate between each table on the page. The accessible name is provided by 'aria-labelledby' > 'aria-label'> caption > 'title' > 'summary'. If two tables contain the same information then number them in the accessible name. See Understanding 1.3.1.
E898
[WCAG21 2.4.6 (AA)] Heading with no content
Ensure that all headings contain informative content. This is necessary because users may navigate or search by headings. See Understanding 2.4.6.
[WCAG21 2.4.6 (AA)] Form control labels must be unique
Use unique labels so that users can distinguish between form controls on the same page. Alternatively, place them within different <fieldset> with unique <legend> labels, because the legend text is read out along with the label text. See WCAG 2.1 Success Criterion 2.4.6.
[WCAG21 2.4.6 (AA)] Provide descriptive text
Any descriptive text supplied should be clear. See WCAG 2.1 General Technique G131.
E887
[WCAG21 2.4.7 (AA)] Do not remove focus when focus is received
The system focus indicator is an important part of accessibility for keyboard users. Removing focus entirely means the content can only be accessed by a pointer device. See WCAG 2.1 Failure F55.
[WCAG21 2.4.7 (AA)] Do not remove the visual focus indicator or render it invisible
Turning off the focus indicator, or using styling which may make it difficult to see the focus indicator, prevents people from knowing which element has the keyboard focus. See WCAG 2.1 Failure F78.

Reference > WCAG21 Level AAA

Issues due to failing to meet the WCAG21 Level AAA accessibility guidelines

Code
Summary
Details
[WCAG21 1.4.6 (AAA)] Large text within this element has a low contrast ratio. Detected ratio: RATIO
Ensure that the visual presentation of large text has a contrast ratio of at least 4.5:1, so that's it's easy to read. Note that our contrast ratio calculation does not account for background images, gradients or text shadows. See WCAG 2.1 Success Criterion 1.4.6.
[WCAG21 1.4.6 (AAA)] Text within this element has a low contrast ratio. Detected ratio: RATIO
Ensure that the visual presentation of text has a contrast ratio of at least 7:1, so that's it's easy to read. Note that our contrast ratio calculation does not account for background images, gradients or text shadows. See WCAG 2.1 Success Criterion 1.4.6.
[WCAG21 1.4.8 (AAA)] You should not use justified text
Many people with cognitive disabilities have a great deal of trouble with blocks of text that are justified (aligned to both the left and the right margins). See WCAG 2.1 Failure F88.
E887
[WCAG21 2.1.3 (AAA)] Do not remove focus when focus is received
The system focus indicator is an important part of accessibility for keyboard users. Removing focus entirely means the content can only be accessed by a pointer device. See WCAG 2.1 Failure F55.
E891
[WCAG21 2.1.3 (AAA)] Server-side image maps are not keyboard accessible
Server-side image maps are not keyboard accessible. Consider an accessible alternative instead. See Understanding 2.1.1.
W884
[WCAG21 2.1.3 (AAA)] Mouse/Pointer event handlers require keyboard equivalents
When using mouse/pointer event handlers, ensure that you provide an equivalent keyboard handler. See WCAG 2.1 Failure F54.
E901
[WCAG21 2.2.4 (AAA)] You should not use a non-zero page redirect
It is important that the time-out is set to zero, to avoid content being displayed before the new page is loaded. See WCAG 2.1 Failure F40.
E882
[WCAG21 2.2.4/3.2.5 (AAA)] You should not use a non-zero page refresh or redirect
It is important that the time-out is set to zero, to avoid that content is displayed before the new page is loaded. See WCAG 2.1 Failure F41.
E867
[WCAG21 2.4.9 (AAA)] Unnecessary duplication of link text. See matching tag on line: LINE_NUMBER
A 'stuttering' effect occurs when you have two adjacent links with the same link text. Consider combining the links into one and removing any redundant link text. See WCAG 2.1 HTML Technique H2.
E868
[WCAG21 2.4.9 (AAA)] Unnecessary duplication of link text. See matching tag on line: LINE_NUMBER
A 'stuttering' effect occurs when you have attributes or 'alt' text of images within the link with the same link text. Consider removing the 'alt' text of the image where the link text already provides the context for the image. See WCAG 2.1 HTML Technique H2.
P871
[WCAG21 2.4.9 (AAA)] Link text is missing
Describe the purpose of a link by providing descriptive text as the content of the element. The description lets a user distinguish this link from other links in the Web page and helps the user determine whether to follow the link. The URL of the destination is generally not sufficiently descriptive. See WCAG 2.1 HTML Technique H30.
W885
[WCAG21 2.4.9 (AAA)] Do not use the URL as link text
Describe the purpose of a link by providing descriptive text as the content of the <a> element, or provide an 'aria-label' or 'aria-labelledby' attribute. The description lets a user distinguish this link from other links in the Web page and helps the user determine whether to follow the link. The URL of the destination is generally not sufficiently descriptive. See WCAG 2.1 HTML Technique H30.
[WCAG21 2.4.9 (AAA)] Provide descriptive link text
You should always provide a way of allowing users to know the destination from the link text alone. See WCAG 2.1 Failure F84.
W861
[WCAG21 2.4.9 (AAA)] Is the 'title' text deliberately empty?
The 'title' attribute is used to provide additional information to help clarify or further describe the purpose of a link, but it has been found to be empty. You may wish to check that the title text has not simply been forgotten. See WCAG 2.1 HTML Technique H33.
W869
[WCAG21 2.4.10 (AAA)] Use heading elements to convey structure
Many assistive technologies provide navigation using headings, including skipping navigational links. If your document has any structure you should use heading markup to convey the structure of the content. Even a single header will make it easier for users. See WCAG 2.1 HTML Technique H69.
[WCAG21 3.1.3/3.1.4/3.1.6 (AAA)] No spell check was selected
Performing a spell check will help correct any misspelt words which screen readers may mispronounce and confuse users. It can also be used to identify unusual words, acronyms and abbreviations which may not have been explained. See WCAG 2.1 Guideline 3.1.
[WCAG21 3.1.4 (AAA)] Add a 'title' attribute to the element to describe it
Ensure that <abbr> and <acronym> elements have a 'title' attribute that describes the abbreviation/acronym. See WCAG 2.1 HTML Technique H28.