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Michael W Moser commented on NIFI-4298: --------------------------------------- NIFI-8971 partially resolves this, by fixing the specific MergeContent problem in the description. > NiFi allows users to remove critical Attributes that are needed by processors. > ------------------------------------------------------------------------------ > > Key: NIFI-4298 > URL: https://issues.apache.org/jira/browse/NIFI-4298 > Project: Apache NiFi > Issue Type: Bug > Components: Core Framework > Affects Versions: 1.2.0 > Reporter: Matthew Clarke > Priority: Major > > The UpdateAttribute processor provides users with the ability to provide a > "Delete Attributes Expression". > While FlowFile properties entryDate, lineageDate, fileSize, and uuid are > protected and can not be removed, FlowFile attributes path and filename can > be removed. > Removal of these attributes has adverse affects on many other processors. > Any processor that will write a FlowFile out requires the filename attribute. > In addition, I have found that the MergeContent processor (configured to use > FlowFileStreams as the merge strategy). also, for whatever reason, requires > that the path attribute exists on the FlowFile. > If this attribute is missing, a NPE is thrown and the session is rolled back. > 2017-08-14 19:27:00,156 ERROR [Timer-Driven Process Thread-7] > o.a.n.processors.standard.MergeContent > MergeContent[id=d7213e1f-0c03-1715-93cc-b1be9228ec36] Failed to process > bundle of 1 files due to java.lang.NullPointerException; rolling back > sessions: {} > A stack trace is not produced even if DEBUG is enabled for this processor. > NiFi needs to prevent users from being able to remove attributes which may be > "required" by other processors. -- This message was sent by Atlassian Jira (v8.20.10#820010)