NFS Datastore Mount Fails on ESXi Host with Error Unable to Connect to NFS Server
Article ID: 393660
Updated On:
Products
Issue/Introduction
When attempting to mount an NFS datastore on an ESXi host, the storage operation fails. The vSphere Client displays an error indicating a host configuration failure, and the mounting process terminates.
The /var/log/hostd.log file contains the following error signatures:
2025-04-04T17:21:29.102Z error hostd[2101497] [Originator@6876 sub=Hostsvc.FSVolumeProvider opID=<REDACTED_SECRETS> user=vpxuser:<REDACTED_SECRETS>] VmkCtl mount or ProcessNas failed: Mount failed: Unable to complete Sysinfo operation. Please see the VMkernel log file for more details.: Unable to connect to NFS server
2025-04-04T17:21:29.113Z info hostd[2101497] [Originator@6876 sub=Solo.Vmomi opID=<REDACTED_SECRETS> user=vpxuser:<REDACTED_SECRETS>] Throw vim.fault.PlatformConfigFault
2025-04-04T17:21:29.113Z info hostd[2101497] [Originator@6876 sub=Solo.Vmomi opID=<REDACTED_SECRETS> user=vpxuser:<REDACTED_SECRETS>] Result:
--> (vim.fault.PlatformConfigFault) {
--> faultMessage = (vmodl.LocalizableMessage) [
--> (vmodl.LocalizableMessage) {
--> key = "com.vmware.esx.hostctl.default",
--> arg = (vmodl.KeyAnyValue) [
--> (vmodl.KeyAnyValue) {
--> key = "reason",
--> value = "Mount failed: Unable to complete Sysinfo operation. Please see the VMkernel log file for more details.: Unable to connect to NFS server"
--> }
--> ],
--> }
--> ],
--> text = "",
--> msg = ""
--> }
The /var/run/log/vmkernel.log file contains corresponding synchronous RPC cancellation entries:
2025-06-23T08:58:14.955Z In(182) vmkernel: cpu60:2099267 opID=##)SunRPC: 3615: Synchronous RPC cancel for client <REDACTED_SECRETS> IP <REDACTED_IPS> proc 3 xid <REDACTED_SECRETS> attempt 1 of 3
2025-06-23T08:58:24.955Z In(182) vmkernel: cpu60:2099267 opID=##)SunRPC: 3615: Synchronous RPC cancel for client <REDACTED_SECRETS> IP <REDACTED_IPS> proc 3 xid <REDACTED_SECRETS> attempt 2 of 3
2025-06-23T08:58:34.956Z In(182) vmkernel: cpu60:2099267 opID=##)SunRPC: 3615: Synchronous RPC cancel for client <REDACTED_SECRETS> IP <REDACTED_IPS> proc 3 xid <REDACTED_SECRETS> attempt 3 of 3
2025-06-23T08:58:34.956Z In(182) vmkernel: cpu60:2099267 opID=##)StorageApdHandler: 1051: Freeing APD handle <REDACTED_SECRETS> [<REDACTED_SECRETS>]
2025-06-23T08:58:34.956Z In(182) vmkernel: cpu60:2099267 opID=##)StorageApdHandler: 1135: APD Handle freed!
2025-06-23T08:58:34.956Z In(182) vmkernel: cpu60:2099267 opID=##)NFS: 3500: NFS mount Environment
VMware vSphere ESXi
Cause
The ESXi host cannot establish a connection to the designated remote NFS server over the network on the required TCP port (2049) or the Jumbo Frame ICMP payload size is blocked across the layer 2/3 transport topology.
Resolution
Establish an SSH session to the affected ESXi host as root.
Execute a jumbo-frame enabled ping test explicitly bound to the corresponding storage VMkernel interface to verify network connectivity to the NFS endpoint:
vmkping -I <vmkernel_ID> -s 8972 -d <NFS_Server_IP>
Note: If packets are lost (100% packet loss), verify upstream physical switch configurations, routing tables, and MTU parity (9000 end-to-end) across the storage path.
Execute the nc (netcat) utility to validate that firewall policies or security groups on the network or the storage array are not dropping traffic on the mandatory NFS daemon port:
nc -zv <NFS_Server_IP> 111
nc -zv <NFS_Server_IP> 635
nc -zv <NFS_Server_IP> 2049
If the netcat command reports a timeout or connection failure, adjust external network ACLs, firewalls, or the target NFS server daemon configuration to permit traffic from the ESXi VMkernel IP address over TCP port 2049.
Refer to the related KB : NFS Datastore Fails to Mount with "The mount request was denied by the NFS server" Error
Additional Information
For instances where connectivity succeeds but the server rejects the presentation, reference: NFS Datastore Fails to Mount with "The mount request was denied by the NFS server" Error
For general triage, reference: Troubleshooting NFS datastore connectivity issues
- For connection issues: Unable to connect to NFS server
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