is it required to do unlocking of bootloader before installing and upgraded rom for sm-g550t galaxy on5 and then reroot i want to know,in order to upgrade from my rooted Samsung ON 5 SM G550T, to Nougate 7.00, will i have to re-root the phone process again. Currently my phone is rooted but i think my boot loader is locked, which will require me to unlock my boot loader; in order to do a upgrade to Nougate,if i understand?
 If the boot loader is locked how do i check? to see if its locked.
On a previous occasion i tried to flash xposed program (rom) and got a binary 1 error is this related to a locked boot loader, or diff issue. If so how do fix a binary 1-2 error message.
As Samsung hasn't updated your device to android 7.0 so in order to upgrade your android version you have to unlock bootloader then flash a custom recovery.

Then you can flash any 7.0 custom rom.