Originally Posted by cruise350
Waiting for the OP to post back if he was successful in downgrading MK2 to MJA by running the full MJA tar file. I know you can't go back farther than MJA but hoping we can at least downgrade back to MJA if we need to after a failed upgrade or bad ota.
I had the exact same problem as the OP with wifi and KNOX notifications upon toggling wifi. This had to do with a bad update which I believe was a result of rooting my phone. Something is weird with recovery after rooting the phone with cf autoroot as it no longer looks like the stock MJA recovery. So when I manually installed the MK2 update using what I believed was the stock recovery, I experienced serious issues such as what the OP described.
In any case, I used ODIN to flash the MJA tar which restored everything back to normal. Then I used the stock recovery to apply the update zip file and everything went without a problem. Then I flashed cf autoroot with ODIN and again, the recovery looks different from the stock MJA and MK2 recovery, but everything works fine. I did not do a data wipe during any step of the process and have seen no ill effects so far.
So the take home message is, if you rooted the phone ODIN stock MJA or MK2 if it becomes available before applying any future updates manually. Or ODIN a stock recovery file for your current ROM if one is available. KNOX has nothing to do with this. I disabled KNOX and still could not turn on wifi.