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Tripped knox/unlocked bootloader means that you cannot use OTA anymore.
Best regards,Mikey. For any more questions,PM me. I hope you found what you were looking for.
Sent from my Samsung Galaxy S7 Edge SM-G935F.
Tripping know doesn't prevent OTA. A tab 2 won't have knox either. The OP just needs to find the latest fw and flash with Odin. King root will have messed up OTA