I installed/compiled my Bitcoin Core RPC client version v0.16.2.0 and i used --disable-wallet flag.
I think this is the reason I am seeing "Method not found" errors when trying to GetNewAddress
how can i install/enable it after having fully confirmed node with up to date blockchain?
os: Ubuntu 16.04.5
accepted the answer below but in my case since i set it up sing apt-install bitcoind the wallet feature was already there, i just needed to flip the disablewallet=1 flag in my bitcoin.config