Your i9506 phone was originally on CSC code
TEN which is the code for Norway, Telenor.
At some point in the past, it has been flashed with NEE = Nordic Countries firmware.
This has caused a mismatch in the codes and will prevent you receiving further updates. See #1.4 29 Galaxy S4 models - know yours?
The latest release for your CSC code Telenor is Android 4.3....
Model: GT-I9506
Model name: GALAXY S4 LTE-A
Country: Norway (Telenor)
Version: Android 4.3
Changelist: 2210443
Build date: Wed, 18 Dec 2013 11:46:45 +0000
Product Code: TEN
PDA: I9506XXUBML6
CSC: I9506TENBML2
MODEM: I9506XXUBMK7
This is the version of the firmware that should be on your phone. However, the
NEE code has had 3 releases for Android 4.4.2 and is now on the following...
Model: GT-I9506
Model name: GALAXY S4 LTE-A
Country: Nordic countries
Version: Android 4.4.2
Changelist: 2986314
Build date: Mon, 13 Oct 2014 10:37:00 +0000
Product Code: NEE
PDA: I9506XXUCNJ1
CSC: I9506NEECNJ1
MODEM: I9506XXUCNF3
Since
TEN, Telenor have not issued an update since February 2013 and are still on Android 4.3 and show no signs of releasing Android 4.4.2. You may wish to manually update your phone to the Android 4.4.2,
NEE, Nordic Countries firmware by following the instructions and video in
#1.5 of
29 Galaxy S4 models - know yours?
Alternatively, you could take it to a Samsung Service Point and they could restore you to the Android 4.3,
TEN, firmware. They may charge for this as it is outside of the warranty terms.