PDF Accessibility Checker Errors — How to Fix Them
PDF accessibility compliance is increasingly required — by US federal agencies under Section 508, by European organisations under EN 301 549, and by any organisation that takes WCAG (Web Content Accessibility Guidelines) seriously. When you run Adobe Acrobat's accessibility checker or a third-party tool, a long list of errors can appear — missing alt text, no document title, untagged content, wrong reading order, tables with no headers. Each error type has a specific fix, and understanding what the error actually means makes the remediation process less overwhelming. Some errors require the original source document to be fixed and re-exported. Others can be fixed directly in the PDF. This guide covers the most common accessibility errors and the fastest paths to fixing each one.
Fix Missing Document Title and Metadata
Missing document title is one of the easiest accessibility fixes. Screen readers announce the document title when a user opens the file, giving context about what they're viewing. Without a title, the screen reader announces the filename — often meaningless like 'doc-2024-0312-v3.pdf'. To fix this without Acrobat Pro, convert the PDF to Word using LazyPDF, set a proper document title in File → Properties in Word, then re-export to PDF. Make sure 'Document structure tags for accessibility' is checked in the PDF export options. In Word's PDF export, look for Options → Document properties to include.
- 1Convert the PDF to Word using lazy-pdf.com/pdf-to-word.
- 2In Word, go to File → Info and set the document Title property.
- 3Go to File → Save As → PDF, click Options, and check 'Document structure tags for accessibility'.
- 4Save the PDF and re-run the accessibility checker to confirm the title error is resolved.
Address Missing Alt Text on Images
Every meaningful image in an accessible PDF needs alternative text that describes its content to screen reader users. Decorative images should be marked as 'artefacts' so screen readers skip them. Missing alt text errors appear for every image without a description. Fixing alt text in PDFs requires Acrobat Pro or a specialised PDF tagging tool like CommonLook or PAC. Without Acrobat Pro, the most practical approach is to fix alt text at the source: add alt text to all images in Word (right-click image → Alt Text), then re-export. For PDFs without editable source documents, you'll need Acrobat Pro's Reading Order tool to add alt text to the tag tree.
Fix Untagged Content and Reading Order
PDF accessibility requires a 'tag tree' — a structured representation of all content with semantic roles (heading, paragraph, figure, table, list). PDFs created by simply printing to PDF or scanning lack this structure entirely. The accessibility checker will report 'document is not tagged' as a high-priority error. The fastest path to a tagged PDF is to fix the source document. In Word, use proper Heading styles (Heading 1, Heading 2, etc.) instead of manually formatted bold text. Use proper table markup. Export with accessibility tags enabled. For PDFs without a source document, Adobe Acrobat Pro's Accessibility Tools → Auto-Tag feature can add an automatic tag structure, though it requires manual review and correction for complex layouts.
- 1Convert the PDF to Word at lazy-pdf.com/pdf-to-word.
- 2Apply proper Heading styles to all headings in Word (Heading 1, Heading 2, etc.).
- 3Ensure tables use proper table markup and have header rows identified.
- 4Export to PDF with 'Document structure tags for accessibility' option enabled.
Handle Scanned PDFs and Accessibility
Scanned PDFs are inherently inaccessible — they're images with no text, structure, or alt text. To make a scanned PDF accessible, you need two steps: first, run OCR to add a text layer (LazyPDF's OCR tool), then add structural tags either through Acrobat Pro's auto-tag function or by converting the OCR output to Word, applying proper structure, and re-exporting. OCR alone satisfies the most critical accessibility requirement — that text content is machine-readable. But full WCAG compliance for scanned documents requires additional tagging work that typically needs Acrobat Pro or specialised accessibility tools.
Frequently Asked Questions
What's the minimum I need to fix to meet basic PDF accessibility requirements?
For basic compliance, prioritise in this order: (1) Ensure the document has a text layer — scan+OCR if needed. (2) Set a meaningful document title. (3) Ensure the document is tagged with basic structure. (4) Add alt text to meaningful images. These four items address the most critical access barriers. Full WCAG AA compliance requires more work on reading order, colour contrast, and form field labels, but these four items cover the most impactful issues.
My PDF accessibility checker shows 'Needs manual check' — what does that mean?
Some accessibility requirements cannot be verified automatically because they require human judgement. 'Needs manual check' items include: alt text appropriateness (the checker can confirm alt text exists but not whether it's meaningful), colour contrast (tools can check ratios but not context), and logical reading order (tags may exist but a human must verify the sequence makes sense). These items require a person to review and correct them — the checker can't do it for you.
Do PDFs created from Word automatically pass accessibility checks?
Not automatically — they pass some checks but not all. Word PDFs include the basic tag structure when exported correctly, and they inherit Word's heading hierarchy. However, images still need manual alt text, tables need defined headers, the document language must be set, and reading order should be verified. A Word-exported PDF typically has far fewer accessibility errors than a scanned or print-to-PDF document, but still needs review before claiming full compliance.