现象：

1. 自动备份好长时间没有进行了（或者每次进行都失败了？）
2. 进入iCloud显示超过10个星期没有备份了
3. 开始手动备份，显示剩余时间逐渐上升，从1分钟到1个小时，最后显示“备份无法进行”

解决：

1. Plug iphone to USB
2. Turn off in iTunes “backup to iCloud” by choosing “backup to this computer”
3. Sync
4. Go to iCloud and delete all previous backups.
5. Turn on in iTunes “backup to iCloud”.
6. In iPhone click backup to iCloud

来源：http://www.jailbreakqa.com/questions/147400/cant-backup-to-icloud-backupd-is-crashing-because-of-musiclibrary/156372