@Shampy  You are saying that with no flow.json.gz file present, NIFi throws above exception on startup.  With No flow.json.gz file, NiFi will create one during startup. I also suggest using the official Apache NiFi 2.x release and stop using the pre-release Maintenance releases that were put out during development of NiFi 2.x.  There were 4 maintenance (M1 - M4) releases put out before the first official release of Apache NiFi 2.0.0. The latest official release ofd Apache NiFi 2.x is NiFi 2.2.0 which can be downloaded from here: https://nifi.apache.org/download/ Please help our community thrive. If you found any of the suggestions/solutions provided helped you with solving your issue or answering your question, please take a moment to login and click "Accept as Solution" on one or more of them that helped. Thank you, Matt ... View more