When you upgrade the cluster, consider if your MapR client or your MapR POSIX client needs to be upgraded as well. See Planning Upgrades to MapR Clients.
Additionally, MapR POSIX loopbacknfs clients can be migrated to FUSE-based POSIX clients on Basic POSIX client packages. MapR POSIX loopbacknfs clients can not be migrated to Platinum POSIX client packages.
See Migrating to FUSE-based POSIX Clients for more information.