SocketDir=/var/run/zabbix
stands for Inter-Process Communication . In the context of Zabbix, the Agent often runs as a daemon with multiple processes (a parent process and several child processes or threads) to handle checks efficiently. zabbix cannot write to ipc socket broken pipe
Start with the simplest fix – increase Timeout – and then work your way up to process tuning and filesystem checks. Zabbix opens many sockets and files
Zabbix opens many sockets and files. If it hits the OS limit, communication fails. Check limits: ulimit -n This is distinct from a "Connection refused" error
Proxies often log cannot write to IPC socket when the main server is unreachable, and the local proxy processes start failing internally.
This is distinct from a "Connection refused" error (which usually means nothing is listening). A "Broken Pipe" implies a connection existed , but the remote end crashed or closed it prematurely.
If your Zabbix TmpDirectory (where IPC sockets are stored) is on NFS, tmpfs, or an unreliable mount, you’ll see broken pipes.