Hi @lben ,   It seems what you need is the Wait\Notify processors . For more information on how to use those processors : https://pierrevillard.com/2018/06/27/nifi-workflow-monitoring-wait-notify-pattern-with-split-and-merge/ https://www.youtube.com/watch?v=ALvzZ6D4GtA   let me know how that works for you. If that helps please accept solution. Thanks ... View more

Not ruling out something environmental here, but what is being observed is validation working and processor execution not while both those processes should be using the same basic code. The 3 loggers that would produce Debug logging output suggested in my previous post may shed more light on the difference in the output logging when validation is done versus running (starting) the processor.  So that is probably the best place to start. ... View more