Event keeps appearing in ESX UI "Failed - The requested operation is not implemented by the server"

Products

• VMware vSphere ESXi

Issue/Introduction

• The following message keeps appearing in ESX UI.
  

  The requested operation is not implemented by the server

• Can be seen under "event notifications" in ESX UI.
  
• Reviewing ESX log </var/run/log/hostd.log>  shows a similar error.
  

  <timestamps> UTC In(166) Hostd[2099066]: [Originator@6876 sub=AdapterServer opID=######## sid=######## user=root] AdapterServer caught exception; <<########-####-####-####-e7f58f3976e4, <TCP '127.0.0.1 : 8307'>, <TCP '127.0.0.1 : 32678'>>, ha-sessionmgr, vim.SessionManager.sessionIsActive, <vim.version.v8_0_3_0, official, 8.0.3.0>, [N11HostdCommon18VmomiAdapterServer19ActivationResponderE:0x000000e609a3e028]>, N5Vmomi5Fault14NotImplemented9ExceptionE(Fault cause: vmodl.fault.NotImplemented

Environment

VMware vSphere ESXi

Cause

• Malformed or Incorrect API's are being sent to ESXi.
• Review ESXi logs <var/run/log/hostd.log> to identify the IP/User issuing these API calls to affected ESX host.
  

  <timestamps> UTC In(166) Hostd[2098725]: [Originator@6876 sub=Vimsvc.HaSessionManager opID=######## sid=########] Accepted password for user root from #.#.#.# - session=########-####-####-####-e7f58f3976e4
  
  <timestamps> UTC In(166) Hostd[2099066]: [Originator@6876 sub=AdapterServer opID=######## sid=######## user=root] AdapterServer caught exception; <<########-####-####-####-e7f58f3976e4, <TCP '127.0.0.1 : 8307'>, <TCP '127.0.0.1 : 32678'>>, ha-sessionmgr, vim.SessionManager.sessionIsActive, <vim.version.v8_0_3_0, official, 8.0.3.0>, [N11HostdCommon18VmomiAdapterServer19ActivationResponderE:0x000000e609a3e028]>, N5Vmomi5Fault14NotImplemented9ExceptionE(Fault cause: vmodl.fault.NotImplemented

Resolution

• Identify the server/user which is issuing these calls and pause whatever actions are generating these messages.