Github user alopresto commented on the issue:
https://github.com/apache/nifi/pull/2164
Verified that deleting the `/docs` directory before starting the app. The
app comes up fine and this line is present in the log.
`2017-09-28 13:27:36,717 INFO [main] org.apache.nifi.web.server.JettyServer
Directory 'docs' is missing. Some documentation will be unavailable.`
Ran `contrib-check` and all tests pass. +1, merging. ---
