This is a bug in NiFi. I found that codes are updated in this ticket to handle connection unavailable [NIFI-10265] PutDatabaseRecord hangs and keeps file in queue when DB is unavailable instead of sending to fail - ASF JIRA with Nifi version 1.17.0.   You should upgrade NiFi to a newer version which will route connection unavailable error to failure relationship where you can setup retry policy to handle it. ... View more