>btw: Recent ONTAP versions return NFS4ERR_STALE_CLIENTID which is handled correctly - Linux client will try to renew its lease and if successful it will retry open(). One more comment here, although the issue won't manifest to applications with NetApp fileservers in this case, it is still wrong for the client to end up in such a state. Also, you will need to wait longer (keep unmounting/mounting) with NetApp filers as they seem to have implemented courtesy locks/delayed lease expiration as per the RFC. This means to reproduce the issue against NetApp you need to wait at least 2x grace period + 1 minute). Best regards, Robert Milkowski