The coin-miners and hashvalue pools seems to reject shares from older mining clients. Try using the newest CPUminer-opt-3.8.3 version.
I am using 3.8.3.3
I get "stratum_recv_line failed" on all other pools after submitting a few shares
I get that occasionally as well. Sometimes it will happen and not recover for more than 5 minutes so i switch pools. Shitty situation honestly. Im just holding out for the Dev to hopefully start up a legit pool that makes everyone happy.