Update slow , preparing for long moments

Define “taking a long time”. Depending upon available free-space into which the update can be un-packed and verified prior to commencing update of the device, the “preparing” phase can take a while. The update process may also automatically offload some Apps or data; the speed of your internet connection may impact time required.

You would be well advised to keep your iPad connected to its Power Adapter throughout the update process for two reasons:

1) Connection to external power will keep your network connection active.

2) The external power source helps to protect against an update failure caused by a failing battery.

Whilst there is no defined time period, if your device remains in the “preparing” phase for an hour or more, it may be reasonable to assume that something has stalled. If this occurs, attempt to cancel the installation - prior to restarting the iPad and the update.