Update error from Android 4.4.4 on Vodafone Smart Tab 4G

[Android Central Question]

Hi, I've been trying to update my tablet for ages now and it always ends up in an error. It says:
E:erasing fota.status failed errno=2
...
"/custpack/JRD_custres/app/Gallery2-res.apk" has unexpected contents.
E:Error in /cache/update.zip
(Status 7)

What could I do to make it update?
Thanks