Plugin has no init() entry point.
The plugin (loadable module) architecture demands that each plugin provides an initialization entry point to the rsyslog core. Without it, the plugin is invalid.
During the load of a module, the rsyslog core could not find this init() entry point (it tries so via dlload()/dlsysm()). This most probably is an indication of one of the following failure conditions:
a) the plugin file is corrupt
b) there is a permission problem
c) the file in question is not a plugin file