Elasticfence - Invalid User

I have installed the plugin "Elasticfence" (for Basic HTTP Auth for my ES 2.3.2). And wrote the following two lines in my elasticsearch.yml:

elasticfence.disabled: false
elasticfence.root.password: rootpassword

When I restart the cluster, I keep getting this over and over again in the log file:

[INFO ][plugin.elasticfence ] Invalid User: /_bulk
[INFO ][plugin.elasticfence ] Invalid User: /

What am I to do to avert this? Is there any setting I missed?

You should ask on the repo for that as the author may not frequent these forums.