Github user mattyb149 commented on the issue:
https://github.com/apache/nifi/pull/2175
Before the fix, you would probably see a log statement for each failed doc.
Also for some "not found" errors, such as maybe deleting a doc that doesn't
exist? you would see an empty reason. The fix includes only logging one error
per batch, and filling in the empty reason for the "not found" errors.---
