Error when trying to mount NFS share from NAS (Openmediavault) in Proxmox

 I was getting the error: 

create storage failed: mkdir /mnt/pve/nfsNAS/dump: Permission denied at /usr/share/perl5/PVE/Storage/Plugin.pm line 1389. (500) 

 When I tried to mount my NFS share created in Openmediavault using the GUI in Proxmox. I tried everything and thought it was a permission error but I could not pinpoint it.

The solution is very simple and I found it on Truenas forum (through google): 

Proxmox requires "no_root_squash" when connecting to a NFS server.

So in the share settings / connection settings of the NFS share on your NAS add that parameter and you can now add the NFS share as storage in Proxmox 

The forum thread: https://www.truenas.com/community/threads/am-i-too-dumb-to-understand-nfs-permissions.86524/