Syslog-ng PE Not Receiving Connections; Number of allowed concurrent connections reached, rejecting connection (4234885)

Resolution - Cause 1

In the sources section of the Syslog-ng PE configuration file (syslog-ng.conf) set the option max-connections(n) to a number large enough to fit all clients sending logs to that source. See example source configuration below where max-connections(n) has been substituted for 300.

source s_localhost {
        network(
                ip(127.0.0.1)
                port(1999)
                transport("tcp")
                max-connections(300)
        );
};

Resolution - Cause  2

The flow-control was activated because of an inaccessible destination.
The problem can be fixed by making available the remote destination.

To do that, you have to check the root cause of the connection issue, that can be different, for example

• a connectivity issue because of networking (network outage, firewall etc.)
• the application at the remote server has an issue and cannot accept logs

If the remote destination was stopped on purpose, remove it from the logpathes in syslog-ng-conf, then restart syslog-ng.