Hi, I use the following conf file to start syslog-ng 3.7.3 complied with Java supported version and got the following error: # syslog-ng -f /opt/syslog-ng/syslog-ng.conf [2016-05-03T23:13:54.191256] Can't find class; class_name='org/syslog_ng/SyslogNgClassLoader' ** ERROR:modules/java/native/java_machine.c:126:java_machine_get_class_loader: assertion failed: (self->loader) syslog-ng.conf: @version: 3.7 @include "scl.conf" @module mod-java source s_syslog { syslog(); }; destination d_elastic { java( class_path("/usr/lib64/syslog-ng/java-modules/*.jar:/usr/share/elasticsearch/lib/*.jar") class_name("org.syslog_ng.elasticsearch.ElasticSearchDestination") option("index", "syslog-ng_${YEAR}.${MONTH}.${DAY}") option("type", "test") option("client-mode", "transport") option("server", "sl73ovnapd018") option("port", "9200") option("flush-limit", "10") ); }; log { source(s_syslog); destination(d_elastic); flags(flow-control); }; I found previous post from last year with the exact same error: https://github.com/balabit/syslog-ng/issues/620 According to the post the problem was make install fail to copy "syslog-ng-core.jar" and/or "syslog-ng-common.jar" to target directory. Including these two files in the directory referenced by the class_path should solve the problem. I have these two files included in my class_path already but still got the same error: -rw-r--r-- 1 root root 11411 May 2 06:50 /usr/lib64/syslog-ng/java-modules/syslog-ng-core.jar -rw-r--r-- 1 root root 12536 May 2 06:51 /usr/lib64/syslog-ng/java-modules/syslog-ng-common.jar Any help is highly appreciated. Ming Ho