I have also faced the same issue like iOS crushes on startup. When I was working on MS Office and wanted to converting file in iOS it was showing me an error due to changing pdf. It was stated like MS Office 2013 error 0x4004f00d . I got a important data on it. If you want to reveal may have a look. +1-800-213-8289 MS Office 2013 error code 0x4004f00c or 0x4004f00d[^]