Error when creating a Snapshot Repository

It's better to share the whole stack trace of the exception and the whole error message - even though they can be quite long, they also include useful information.

I'm going to guess that the Elasticsearch process is not running as the same numerical UID or GID on each node, and your NFS configuration does not compensate for this, meaning that when one node creates a subdirectory of the repository it is not possible for the other nodes to modify it.