Nokia E5-00 - Manual (Page 209)

It is recommended that you back up your personal data before updating your device
software.
Warning:
If you install a software update, you cannot use the device, even to make emergency
calls, until the installation is completed and the device is restarted.
Downloading software updates may involve the transmission of large amounts of
data (network service).
Make sure that the device battery has enough power, or connect the charger before
starting the update.
After you update your device software or applications, the instructions in the user
guide may no longer be up to date.
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