check_mk hang on start with mkeventd

1. Starting mkeventd (builtin: snmptrap)...Cannot bind UDP socket for snmptrap to port: Permission denied

chmod u+s /opt/omd/sites/mysite/bin/mkeventd_open514
omd restart

2. It just hang and waiting forever on Starting mkeventd (builtin: snmptrap)...

I found a lot files in /opt/omd/sites/(sitename)/var/mkeventd/status.

Have to manually delete the status and history files to start the mkeventd.