PDF accessibility issues should be repaired in the source file using the authoring application to correct or add accessibility features.

Adobe Acrobat can provide a basic accessibility check for your PDF, but the recommended way is to edit your original file in the source application. 

Accessibility Validation in Adobe Acrobat:

1. Open the PDF document in Adobe Acrobat
   If the Accessibility tools do not show, do the following:
   
   • in Adobe Acrobat Professional, go to View menu, select Tools > Accessibility
   • in Adobe Acrobat DC, click on Tools, and then click on Accessibility under Protect & Standardize heading
     
     
      
     
2. Click on the Accessibility link on the right panel to open the Accessibility tools menu. Then click on the Full Check option.
   
   

    

   
   
3. Click on the Start Checking button​ on the Accessibility Checker Options window.
   
   
   
   
4. The Accessibility Checker displays a report of issues on the left panel.
   

   
   

Repairing Accessibility Issues in Adobe Acrobat:

• Select an issue on the list and then right click to follow the steps to repair it.
  
• Use the Touch Up Reading Order tool to correct or add accessibility features.
  How to use the Touch Up Reading Order tool