PDF Character Encoding Issues - Visually Correct, Accessibility Check Failure

Question

I am encountering a persistent issue with PDF character encoding, specifically with Unicode characters. While the PDFs appear visually correct when opened, accessibility checks are flagging "character encoding failed" errors.

This is happening for both newly converted PDFs and existing ones. I'm concerned about the impact this has on the accessibility of our documents.

Could you please provide guidance on how to diagnose and fix this character encoding problem? Any assistance or suggestions you can offer would be greatly appreciated.

AnandSri · Answer

Hello @Karthik G Kumar

I hope you are doing well, and thank you for reaching out.

When a PDF appears visually correct but fails accessibility checks with the error “character encoding failed”, it typically means that the text in the PDF isn’t properly mapped to Unicode. Screen readers and accessibility tools rely on this mapping to accurately interpret text.

How to Diagnose:

Run Acrobat’s Accessibility Checker:
Go to All Tools > Accessibility > Full Check. Look for “Character encoding failed” errors. See this article for more information: https://adobe.ly/3MPUXDq

Inspect with Preflight:
In Acrobat Pro: Print Production > Preflight > PDF Standards. Check for missing ToUnicode maps or font issues.

Verify Tags and Structure:
Use the Tags panel to confirm text elements are properly tagged and not just images.

Suggestions:

Use a reliable PDF creation method
Export directly from source apps (Word, InDesign) using the "Save as PDF" or Adobe PDF preset, not generic print drivers.
Embed fonts with Unicode mapping
Ensure fonts used in the document support Unicode and are fully embedded.
Recreate or repair the PDF
In Acrobat Pro:
- All Tools > Print Production > Preflight > Fix potential problems (look for “Add missing ToUnicode maps”).
- Alternatively, Save As > Optimized PDF and enable “Tags” and “Fonts”.

Add tags and run Make Accessible
Use All Tools > Accessibility > Make Accessible wizard to add tags and repair encoding.
Check language settings
Set the document language under Menu > Properties > Advanced for better assistive tech interpretation.

I hope this helps.

Regards,

Anand Sri.

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