SMTP worked in OJS 2.3.7 and failed in 3.1.1.2 on same server

@blstzus Hi, We just recently upgraded from 3.1.1 to 3.1.2 and found that the mail/notification delivery system isn’t working anymore. we didnt touch the config file. the point is that when we restore the old version everything works well but with new version we get STMP() error.
Did you find any solution for that?