I'm seeing the following log continuously in the Kubernetes audit log file. Can anyone explain what is this error and its reason

{
"kind":"Event",
"apiVersion":"audit.k8s.io/v1beta1",
"metadata":{"creationTimestamp":"2018-08-29T06:59:04Z"},
"level":"Request",
"timestamp":"2018-08-29T06:59:04Z",
"auditID":"97187fc8-76c1-42f0-9435-c11928b6ec49",
"stage":"ResponseComplete",
"requestURI":"/apis/admissionregistration.k8s.io/v1alpha1/initializerconfigurations",
"verb":"list",
"user":{"username":"system:apiserver","uid":"44rrd678-859a-4f663-bt79-23bar678uj66","groups":["system:masters"]},
"sourceIPs":["X.X.X.X"],
"objectRef":{"resource":"initializerconfigurations","apiGroup":"admissionregistration.k8s.io","apiVersion":"v1alpha1"},
"responseStatus":{"metadata":{},"status":"Failure","reason":"NotFound","code":404},
"requestReceivedTimestamp":"2018-08-29T06:59:04.350346Z",
"stageTimestamp":"2018-08-29T06:59:04.350425Z",
"annotations":{"authorization.k8s.io/decision":"allow","authorization.k8s.io/reason":""}
}