Corrupted files ADE on IPad 6. Since migrating to my IPad 6 mini, from my IPad 4 mini ,

Since I migrated to my IPad 6 mini, from my IPad 4 mini, I have been unable to read books, including the ADE Usera Manual, due to missing pages or parts of pages, I have upgraded to the latest version of ADE. WHat can be done to correct this issue?