I got the "An error has occurred..." after getting a success in sysUpdate and rebooting and nothing else.
If that's your case, you have to get into Recovery Mode (L+R+A+D pad UP while power on) and download the update when when prompted.
If the update dies middle way, try again but turn off wi-fi settings, this will get you to configure your connection settings, there, you have to change your DNS to 8.8.8.8 and 8.8.4.4 for primary and secondary options, reboot again and it should update to 10.3 now