We hope you weren't too attached to Google Play Books' PDF upload support on Android, because you just lost it -- albeit temporarily. Following some code sleuthing, Android Police has confirmed that Google removed PDF uploading; for now, you're limited to transferring EPUB books. The PDF support was experimental, Google says, and should come back with a future app update. That's unfortunate for anyone hoping to save documents to Play Books, but we won't object too much when there are at least a few alternatives for sending PDFs to the cloud.