Module could not be loaded – init failed.
When rsyslog loads a loadable module, it calls an entry point called "init()" inside that module. This message is emitted when the module could be loaded, but init() failed for some reasons. Probable causes could be a version mismatch between the loadable module and the rsyslog core, some third party libraries that could not be loaded or loading the same module more than once (rsyslog tries to prevent this, but if modules are renamed, it may still happen).
Usually, there should be some related error messages right in front of the message in question.