I've tried 1:5.16-2ubuntu0.2 and it looks to fix the reported issue - i.e., commands such as "monit status", "monit restart all", "monit restart all" work as intended, rather than producing the "Invalid action" error message
I've tried 1:5.16-2ubuntu0.2 and it looks to fix the reported issue - i.e., commands such as "monit status", "monit restart all", "monit restart all" work as intended, rather than producing the "Invalid action" error message