"Packet file invailed " means that you the mobile can't access internet through the SIM card,
So here is your problem and its solution :
1-You disabled "update through Wi-fi" and enabled " update using packet data only"
2-You are using Wi-fi mostly
3- You need to go to the setting of "whats app " or the mobile settings itself and mark " allow updates through Wi-fi. or you just charge the SIM card and activate internet services through it.