@Micah Pearce There are numerous ways to accomplish the same result in NiFi. The use of the ${retry.counter:replaceNull('0'):plus(1)} NiFi Expression language statement is to create an attribute with value 1 if attribute "retry.counter" does not exist on the FlowFile; otherwise, the existing value currently assigned to existing attribute "retry.counter" is returned and incremented by 1. - If we just set it to one, each time the same FlowFile passes through this loop it would get set to 1 and would never increment. - Thank you, Matt ... View more