NFS Mount fails Error : Unable to connect to NFS server

Products

• VMware vSphere ESXi

Issue/Introduction

• "NFS datastore mount fails with the error: An error occurred during host configuration. Operation failed, diagnostics report: Mount failed. Unable to complete Sysinfo operation. Please see the VMkernel log file for more details: Unable to connect to NFS server. Connect to the affected ESXi host via SSH as root and review the following log files for the error messages listed below."

• The log file /var/log/hostd.log may contain the message "Mount failed"

  2025-04-04T17:21:29.102Z error hostd[2101497] [Originator@6876 sub=Hostsvc.FSVolumeProvider opID=######-####-auto-###-##:####-##-#-### user=vpxuser:########/] 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=######-####-auto-###-##:####-##-#-### user=vpxuser:#######\#######] Throw vim.fault.PlatformConfigFault
  2025-04-04T17:21:29.113Z info hostd[2101497] [Originator@6876 sub=Solo.Vmomi opID=m1x73n6h-24973346-auto-ev9k3-h5:74274300-2f-8-8493 user=vpxuser:#######\#######] 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 file /var/run/log/vmkernel.log may show a mount failure for the NFS datastore
  
  2025-06-23T08:58:14.955Z In(182) vmkernel: cpu60:2099267 opID=##)SunRPC: 3615: Synchronous RPC cancel for client 0x43########f0 IP ##.###.###.####.0.## proc 3 xid 0x7#####8 attempt 1 of 3
2025-06-23T08:58:24.955Z In(182) vmkernel: cpu60:2099267 opID=##)SunRPC: 3615: Synchronous RPC cancel for client 0x43########f0 IP ##.##.###.1##.0.### proc 3 xid 0x7#####8 attempt 2 of 3
2025-06-23T08:58:34.956Z In(182) vmkernel: cpu60:2099267 opID=##)SunRPC: 3615: Synchronous RPC cancel for client 0x43########f0 IP 10.##.##.1##.0.1## proc 3 xid 0x7#####8 attempt 3 of 3
2025-06-23T08:58:34.956Z In(182) vmkernel: cpu60:2099267 opID=##)StorageApdHandler: 1051: Freeing APD handle 0x43########60 [1######3-c######0]
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 failed for <hostname###>:/prd_####### volume ##########. Status: Unable to connect to NFS server.



Environment

VMware vSphere ESXi

Cause

The issue occurs due to a connection failure between the NFS server and the ESXi host.

Resolution

• Log in to the affected ESXi host via SSH as root. Run a vmkping test from the host to the NFS server. Additionally, use the nc (netcat) command to verify if the required network port (TCP 2049) is open. If either test fails with the output shown below, a network connectivity issue exists between the host and the NFS server.
  
  vmkping -I <vmkernel ID> -s 8972 <NFS server IP>
  
  Results:

PING <NFS server IP>: 8972 data bytes
--- <NFS server IP> ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss

• If when running netcat, it fails, then the port is closed 
  
  nc -zv <NFS server IP> port# 

Results:

nc: connect to <NFS server IP> port 2049 (tcp) failed: Connection timed out

Refer to the related KB : NFS Datastore Fails to Mount with "The mount request was denied by the NFS server" Error