Proxmox error (500) adding NFS storage is annoying because the web UI tells you nothing. It just fails. The real error is in the daemon logs, and it’s almost always one of three things: a bad export path, a missing package, or a permissions problem on the NFS server.
Check the export path first
Most of the time the 500 is because the path you typed doesn’t match what the NFS server actually exports. On the TrueNAS side, the export might be /mnt/tank/media but you’re telling Proxmox to use /mnt/tank/media/ or /tank/media. Trailing slash matters. Case matters. Spaces matter.
Run showmount -e <nfs-server-ip> from the Proxmox host. That lists the exact export paths. Copy one of those, paste it into the storage config, and don’t add anything to it.
Missing package: nfs-common
If the export path is right, the next thing to check is whether nfs-common is installed on the Proxmox host. It’s not always there on a fresh install. Without it, the mount fails and the web UI just shows error (500).
apt install nfs-commonThen try adding the storage again. If it still fails, check the daemon log:
journalctl -u pvedaemon -fThat’ll show the actual error instead of the generic 500. You might see something like mount.nfs: access denied by server or mount.nfs: connection refused.
Permissions on the NFS server
If the path is right and the package is installed, it’s permissions. On TrueNAS, the NFS share has a Mapall User and Mapall Group setting. If those are set to root and wheel, Proxmox can’t write to the share because it’s connecting as nobody or some other UID.
Fix it by setting Mapall User to nobody and Mapall Group to nogroup, or whatever UID/GID Proxmox is using. You can also just allow root access on the share if it’s a homelab and you don’t care about security. I’d do that—it’s less to undo later.
If you’re using a different NFS server, the same idea applies: check the export options and make sure the Proxmox host’s IP is allowed to mount it. Sometimes it’s just a missing insecure flag in the export options.
What I’d do
Run showmount -e first. It takes ten seconds and rules out the most common cause. Then check nfs-common. Then look at the daemon log. That order solves 90% of these without touching the NFS server config.
If you’re still stuck, the Proxmox NFS Storage Status Unknown on Second Node post covers a different symptom but some of the same fixes apply.
