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Virtual machine powers off automatically with an error "MXUserAllocSerialNumber: too many locks" (2149941)

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  • MKS error on virtual Machine console.

  • In the vmware.log file, you see entries similar to: 
vcpu-0| E105: PANIC: MXUserAllocSerialNumber: too many locks!
vcpu-0| W115: A core file is available in "/vmfs/volumes/VOLUME_UUID/VM_NAME/vmx-zdump.000"
mks| W115: Panic in progress... ungrabbing
mks| I125: MKS: Release starting (Panic)
mks| I125: MKS: Release finished (Panic)


During normal VM operation, VMware Tools services (version 9.10.0 and later) create vSocket connections to exchange data with the hypervisor. When a large number of such connections are made, the hypervisor may run out of lock serial numbers and the virtual machine powers off with an error.


This is a known issue affecting VMware Tools 9.10.0 and later running in the guests on ESXi 6.0 and later.
For 6.0

This issue is resolved in ESXi 6.0 Patch Release ESXi600-201706001, available at VMware Patch Downloads. For more information on downloading patch, see How to download patches in MyVMware (1021623).

For 6.5
This issue is resolved in ESXI 6.5 Update 1, available at VMware Downloads.

To workaround this issue in ESXi 6.0 and 6.5:

  1. Shut down the virtual machine.

  2. Add  the guest_rpc.rpci.usevsocket parameter to false in the  virtual_machine.vmx file:

    1. Connect to the host running the virtual machine with an SSH session. For more information, see Using ESXi Shell in ESXi 5.x and 6.0 (2004746).

    2. Navigate to the /vmfs/volumes/virtual_machine_datastore/virtual_machine/virtual_machine.vmx file.

    3. Open the virtual_machine.vmx file using a text editor.

    4. Add the guest_rpc.rpci.usevsocket = "FALSE" parameter.

  3. Power on the virtual machine.

See Also

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