ZooKeeper super user can be created and used to fix some permissions issues. This might be the case for example if existing ACLs don't allow access on some zNodes. Typical permissions errors are "Authentication is not valid", "NoAuthException".

First you need to generate a password for the user "super":
$ java -cp "/opt/zookeeper/*:/opt/zookeeper/lib/*" org.apache.zookeeper.server.auth.DigestAuthenticationProvider super:superpwd
This command will produce the following output:
super:superpwd->super:G+ys1zTeJy/1iLhgQS08pRQoMvo=
Edit the file "zkEnv.sh" ("/opt/zookeeper/bin/zkEnv.sh") and set the variable "SERVER_JVMFLAGS":
$ export SERVER_JVMFLAGS="-Xmx${ZK_SERVER_HEAP}m -Dzookeeper.DigestAuthenticationProvider.superDigest=super:G+ys1zTeJy/1iLhgQS08pRQoMvo= $SERVER_JVMFLAGS"
You need to apply the fix for all the ZooKeeper instances of your cluster and restart them all.

Execute the command "zkCli.sh" ("/opt/zookeeper/bin/zkCli.sh") and add a new authentication for the user "super":
[zk: localhost:2181(CONNECTED) 0] addauth digest super:superpwd
You are ready now to perform any operation in "zkCli.sh" that requires special permissions (i.e. reconfig).