Error nfs_perm

Operation not permitted

The server allows you into the folder but refused this particular change. Almost always: changing an owner or group needs root, and the export squashes root.

What this means

NFS status 1, EPERM: not access denied to the folder, but this operation isn’t permitted for who you are. It’s distinct from access denied.

When you’ll see it

• Changing owner or group in the permission editor. On every Unix server, only root can give a file to another user, and nearly every export maps root to nobody (root_squash). Even presenting UID 0 doesn’t help. Change ownership on the NAS itself (SSH sudo chown, or the NAS’s file manager).
• Changing permissions on a file you don’t own. Only the owner (or root) can chmod. Check Inspect Server → “Export owned by” against “You present”.
• Setting timestamps or other attributes on read-only or immutable files.

What helps

Match the UID/GID you present to the file’s owner (the permission editor shows the current owner), or do the change on the server side. See User IDs and squash.