Github user MikeThomsen commented on the issue:
https://github.com/apache/nifi/pull/2749
@mattyb149 @alopresto I backed out the FTP-related changes and put a
temporary fix in there that handles the edge case that was impacting the FTP
processors. There are two cases that cause trouble right now:
1. You pass a null flowfile to the `evaluateExpressionLanguage(FlowFile)`
method while it is set to use flowfile attributes.
2. You pass a null flowfile to that method when it is set to use the
variable registry.
Since, for the time being, the execution framework doesn't care about these
things, I think this should work as a solution until that changes.
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