Acrobat Accessibility Checker Shows Errors — What Each Means and How to Fix
The Acrobat accessibility checker reports specific error codes. Learn what each common error means and the exact steps to resolve it for PDF/UA compliance.
Running Acrobat's Accessibility Checker (Tools → Accessibility → Full Check) and receiving a list of errors does not mean starting over — most errors are fixable with targeted changes in the Tags panel and Reading Order tool. This guide covers the most common errors and the exact steps to resolve each.
Error: "Document is not tagged for accessibility"
Meaning: the PDF has no structure tree at all. Fix: in Acrobat Pro, go to Tools → Accessibility → Add Tags to Document. Acrobat will auto-generate a tag tree from the visual layout. Re-run the accessibility checker after tagging. Auto-generated tags usually have additional errors that need fixing, but this error itself is resolved. For Word documents, add tags at the source by using proper Heading styles before exporting; for scanned documents, OCR first, then tag.
Error: "Alternative text missing" for Images
Meaning: one or more images, charts, or figures lack alt text. Fix: in the Tags panel (View → Navigation Panes → Tags), find Figure tags with no Alt attribute. Right-click each → Properties → Tag tab → enter a meaningful description in the Alternate Text field. For decorative images (borders, dividers, backgrounds): right-click in the Tags panel → Change Tag to Artifact — artifacts are automatically skipped by screen readers. Do not leave alt text blank; blank alt text and missing alt text are treated the same by screen readers.
Error: "Reading order may not be logical" or "Tab order inconsistent"
Meaning: the structure tree order does not match the visual reading order, or form field tab order is wrong. Fix for reading order: go to Tools → Accessibility → Reading Order. The tool shows numbered blocks indicating the reading sequence. Drag blocks to the correct order. For multi-column layouts: column 1 should be read top-to-bottom before column 2. Fix for tab order: in the Pages panel, right-click the page → Page Properties → Tab Order → set to "Use Document Structure." This makes form tab order follow the tag structure order.
Error: "Headings skipped" (H1 followed by H3)
Meaning: the heading hierarchy has gaps — jumping from H1 to H3 without an H2, for example. Screen readers announce heading levels to users; gaps suggest missed content or disorganized structure. Fix: in the Tags panel, find the misleveled heading tag, right-click → Properties → change the Tag to the correct heading level (H2 instead of H3). Verify the logical hierarchy: H1 for document title, H2 for main sections, H3 for subsections. No heading level should be skipped in the sequence.
Error: "Table header cells missing" or "Table cells missing IDs"
Meaning: tables have no TH (header cell) tags, or TH tags lack scope attributes. Screen readers use headers to identify what each column or row means. Fix: in the Tags panel, find TD tags in the table header row. Right-click each → Properties → change Tag to TH. For the scope attribute: right-click the TH tag → Properties → Attribute Editor → add Attribute: Name "Scope," Value "Column" (for column headers) or "Row" (for row headers). Repeat for all header cells. After fixing, re-run the checker to confirm the table passes.
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