Apple yesterday pulled the iOS 9.3.2 update. 9.7-inch iPad Pro users who have not installed iOS 9.3.2 no longer see the update, with iOS 9.3.1 now listed as the most current version of iOS 9 available for download.
Shortly after the release of iOS 9.3.2 some users began reporting an "Error 56" message that instructed them to plug their device into iTunes. Apparently, for those affected, the issue is so severe that Apple is replacing devices that have encountered the bug.
If you’ve run into the problem, contact Apple Support for assistance. The company is looking into the issue but has yet to provide any information as to the cause.