If your validation report contains the warning FactWithNonDisplayableCharacters, then it means that part of the text included in a specific hypertag has not been correctly transformed. The issue occurs during the PDF to xHTML conversion where some characters are recognized as Unicode. You are able to confirm this by checking the 'fact value' found under the Fact List feature. To solve this issue, you will need to find out how your visual component (PDF) has been created. Contact your Customer Support Engineer assigned if you want to learn more about how to solve this and what information you need to relay to your designers.