It's not an error but a warning. Your pool software is not alligned with the new wallet technologies like bitcoin. The 0.16 ufo codebase is alligned with btc. Please upgrade your pool software to allow btc and ufo mining.
Some cmds have been replaced from old codebase.
really thanx bro awesome, but the BIG question is how to upgrade my pool XD
Depending on what pool software you're running you need to check the github and see if they've added a fix..then you can just update from Upstream fairly easily.
I run a few pools and use node-stratum - so I had to update the code there to get my UFO pool working correctly