( Accessibility )
The most common accessibility issues found by RedFlag
Across thousands of scanned pages, the same handful of WCAG failures appear again and again. Here are the top offenders and the fix for each.
The same small set of WCAG failures dominates almost every site we scan: low contrast text, missing alt text, unlabelled form fields, empty buttons and links, missing document language and broken heading order. None of them is exotic, and most take minutes to fix — the problem is they’re everywhere.
1. Low colour contrast (WCAG 1.4.3)
The most frequent failure on the web. Grey-on-white microcopy, placeholder-coloured labels, text over hero images — anything below 4.5:1 for body text (3:1 for large text) fails.
Fix: darken the text or lighten the background until the ratio passes. Design tokens make this a one-place fix; ad-hoc colours make it a hundred-place fix. Contrast failures affect a huge population — low vision, older users, anyone on a phone in sunlight.
2. Images missing alt text (WCAG 1.1.1)
Screen readers announce the filename or nothing at all. AI crawlers get nothing either.
Fix: every <img> needs an alt attribute. Informative images get a description of what the image communicates (“Bar chart showing 40% growth in Q3”, not “chart”). Decorative images get alt="" so assistive tech skips them. The empty string is a decision, not an omission.
3. Form inputs without labels (WCAG 4.1.2, 1.3.1)
Placeholder text is not a label — it vanishes on input and many screen readers don’t treat it as one. An unlabelled field is a mystery box.
Fix: a visible <label for="..."> wired to the input’s id. Where the design genuinely can’t show one, aria-label works — but visible labels help everyone, including users with cognitive disabilities and anyone who forgets what they were typing.
4. Buttons and links with no accessible name (WCAG 4.1.2, 2.4.4)
Icon-only buttons — the hamburger, the ×, the trash can — announce as “button” with no hint of what they do. Links whose only content is an image with no alt announce as their URL.
Fix: aria-label="Close dialog" on icon buttons, or visually hidden text inside them. For links, meaningful text or alt on the image inside. “Click here” and “learn more” fail the same users in a subtler way — the link name should describe the destination.
5. Missing document language (WCAG 3.1.1)
Without <html lang="en">, screen readers guess at pronunciation — English text read with French phonemes is close to unintelligible.
Fix: one attribute on one element, sitewide. The highest fix-per-keystroke ratio in accessibility.
6. Broken heading structure (WCAG 1.3.1, 2.4.6)
Pages with no <h1>, three <h1>s, or jumps from h1 to h4 because the intermediate sizes “looked too big”. Screen reader users navigate by headings; a broken outline means navigating blind. AI systems segment your content by the same outline.
Fix: one h1 naming the page, h2 for sections, h3 inside them. Style size with CSS, never by choosing a different heading level.
7. Keyboard traps and invisible focus (WCAG 2.1.2, 2.4.7)
Modals you can tab into but not out of; outline: none applied globally so keyboard users can’t see where they are.
Fix: never remove focus outlines without replacing them with something clearly visible (WCAG 2.2 tightens this further — see our WCAG 2.2 guide). Test every overlay: Tab through it, Escape out of it.
Why the same issues keep winning
These failures dominate because they’re invisible to the people who ship them. The site looks right; nothing in a typical dev workflow surfaces the problem. Mouse users never meet the keyboard trap, sighted users never hear the missing label.
That’s the case for scanning continuously rather than auditing annually: each of these has an automated rule that catches it the day it’s introduced, mapped to the exact criterion and fix. Fix the top seven and you’ve usually eliminated the majority of raw findings on a site — and materially improved how both assistive technology and AI search read it.
Frequently asked questions
What is the most common accessibility issue on websites?
Low colour contrast is consistently the most frequent failure, followed closely by missing image alt text and unlabelled form controls. All three are detectable automatically and usually quick to fix.
Are the most common accessibility issues hard to fix?
Mostly no. The highest-frequency failures — missing alt text, low contrast, missing labels, empty buttons and links — are typically one-line fixes. The difficulty is coverage, not complexity, which is why continuous scanning matters.
Can automated scanning find all accessibility issues?
No. Automated rules reliably catch the structural failures listed here, which are a meaningful slice of WCAG. Criteria involving judgement — logical focus order, meaningful reading sequence, sensible link purpose — need human review. Use both.