Because I can't find version 3.4.15 button, I submit the issue in version 3.0.28.

I install zabbix-agent-3.4.15 in my machine Ubuntu 18.04.2 LTS. It is work at first. when running a few days, the zabbix-agent service is dead, the log is:

16562:20190809:025045.346 Got signal [signal:15(SIGTERM),sender_pid:3246,sender_uid:0,reason:0]. Exiting ...
16562:20190809:025045.347 Zabbix Agent stopped. Zabbix 3.4.15 (revision 86739).

there are no more information. It is the same situation after i adjust the parameter of DebugLevel to 5 in /etc/zabbix/zabbix_agentd.cof. The service status will be  "inactive (dead)" to "active (exited)" after restart. This is my solution way:

1. apt install libcurl3 zabbix-agent -y
2. service zabbix-agent restart 

It will be ok. But it recurrent in few days. I have deployed 20 machines as agent. There are 3 machines occur the problem. The appendix is zabbix-agent Archive.

That's all. I'm looking forward to your response. Thanks a lot