Currently Being ModeratedJul 18, 2013 2:36 PM (in response to Psychonotes)
Have you tried deleting the digital booklet and redownloading it from the iTunes Store (Downloading past purchases from the App Store, iBookstore, and iTunes Store)?
Currently Being ModeratedAug 7, 2013 12:33 AM (in response to BackgammonThatUp)
I have been having this problem too. Nothing will open the booklets, it always says its an invalid pdf file and it's getting really frustrating. I've deleted and redownloaded numerous times. Nothing works.
Currently Being ModeratedAug 7, 2013 11:51 AM (in response to properploys)
If you have deleted it and redownloaded it but still have the same error, you need to report it as a problem. You can use this link: http://reportaproblem.apple.com