I'm still not sure at this moment.... but....
I think that this is problem related to DAG size increase from ETC.
ETC block 4924220 jumped to next DAG few hours ago.
http://gastracker.io/block/4924220ETC dag increases faster than ETH so their limit will come faster.
So it may caused some problem on maintaining two DAG from claymore. (It uses two DAG for main mining and devfee mining)
I would recommend you to restart the miner.
If it doesn't help, check if it works if -nofee 1 and --allcoins 0 option
Or maybe try other ETC pool from your hardware and tell me the result. I don't see similar error from my gpu, so I don't know what the problem is.
Did not help, it is nothing with the fee, because error comes on the first share. Also it looks like not all worker having this trouble.
Yesterday it helped me as I deleted the Worker on miningpool under Hub Workers
here the same error
https://www.reddit.com/r/EtherMining/comments/7g4kk7/constantly_hitting_this_errorplease_help/Edit: I rebooted the miner computer, after it all normal
Edit2: Finally it did not help, a worker switched again into the state jobnotfound, only computer reboot helps here again, I don't know whats the error