PSOD on 9.1 ESXi host in NFSv41 client stack - NFS41_WorkQueueSubmit

Products

• VMware vSphere ESXi

Issue/Introduction

ESXi 9.1 hosts with NFSv4.1 datastores mounted can encounter PSOD events if there is unstable communication between the hosts and the NFSv4.1 array backing the datastores.

• NFSv4.1 connection flapping may be seen in vmkernel.log.
  • 2026-05-22T06:11:00.928Z -WARNING vmkwarning - [esx@#] cpu24:#) NFS41: NFS41FSAPDNotify:7482: Lost connection to the server X.X.X.X mount point X, mounted as #-#-0000-000000000000 ("X")
2026-05-22T06:11:00.986Z -INFO vmkernel - [esx@#] cpu16:2098598)NFS41: NFS41FSAPDNotify:7547: Restored connection to the server X.X.X.X mount point X, mounted as #-#-0000-000000000000 ("X")
2026-05-22T07:16:23.163Z -WARNING vmkwarning - [esx@#] cpu12:2098598) NFS41: NFS41FSAPDNotify:7482: Lost connection to the server X.X.X.X mount point X, mounted as #-#-0000-000000000000 ("X")
2026-05-22T07:16:23.200Z -INFO vmkernel - [esx@#] cpu12:2098598)NFS41: NFS41FSAPDNotify:7547: Restored connection to the server X.X.X.X mount point S, mounted as #-#-0000-000000000000 ("X")
• Backtrace in the vmkernel-zdump.log and core dump.
  • Panic Message: @BlueScreen: #PF Exception 14 in world 2098598:NFS41SMClusQ IP 0x4200191ea216 addr 0x0
Backtrace:
  0x453912b5be80:[0x4200191ea216]NFS41_WorkQueueSubmit@(nfs41client)#<None>+0x32 stack: 0x431f38cb89e0, 0x42001919d2cc, 0x431f38cb8990, 0xf, 0xf
  0x453912b5bea0:[0x42001919d2cb]NFS41ClusterEventsFromRecov@(nfs41client)#<None>+0x634 stack: 0xf, 0x431f38cb8c28, 0x4312f6a01240, 0x4599aa35eb80, 0x4
  0x453912b5bf00:[0x42001919ad4a]NFS41HandleClusterEvents@(nfs41client)#<None>+0x33 stack: 0x431f38cb89e0, 0x4599aa35eb80, 0x431f38c02d00, 0x4200191dd13a, 0x100000400000004
  0x453912b5bf30:[0x4200191dd139]NFS41_HandleSMEvent@(nfs41client)#<None>+0x32 stack: 0x4200191e9be9, 0x41ffeec1b8a0, 0x4599aa35eb80, 0x4200191e9c3a, 0x4200191e9b80
  0x453912b5bf60:[0x4200191e9c39]NFS41WorkQueueWorkerMain@(nfs41client)#<None>+0xba stack: 0x431f38c02d00, 0x0, 0x0, 0x42001747ceba, 0x0
  0x453912b5bf90:[0x42001747ceb9]vmkWorldFunc@vmkernel#nover+0x46 stack: 0x4200191e9b80, 0x42001747ceb5, 0x0, 0xb2006273e41ddae5, 0x453912b5f000
  0x453912b5bfe0:[0x420017223eeb]CpuSched_StartWorld@vmkernel#nover+0xe8 stack: 0x0, 0x42001740cb28, 0x0, 0x0, 0x0
  0x453912b5c000:[0x42001740cb27]Debug_IsInitialized@vmkernel#nover+0x10 stack: 0x0, 0x0, 0x0, 0x0, 0x0

Environment

vSphere 9.1

NFSv4.1 Storage

Cause

A race condition is hit in the NFSv4.1 client pathing handling.

Resolution

Once the storage connectivity is stabilized, thus the flapping ceases, a reboot of the ESXi host should allow for recovery from this PSOD condition.

A permanent resolution will be included in a future ESXi 9.1.x release