* kube-proxy will emit "FailedToStartNodeHealthcheck" event when fails to start healthz server. ([#49267](https://github.com/kubernetes/kubernetes/pull/49267), [@MrHohn](https://github.com/MrHohn))

    * fixed bugs and improved performance in Stackdriver Sink
* fluentd-gcp addon: Fix a bug in the event-exporter, when repeated events were not sent to Stackdriver. ([#50511](https://github.com/kubernetes/kubernetes/pull/50511), [@crassirostris](https://github.com/crassirostris))

    * [event-exporter addon] Bump event-exporter to 0.2.3 to pick up security fixes.
* PVC may not be synced to controller local cache in time if PV is bound by external PV binder (e.g. kube-scheduler), double check if PVC is not found to prevent reclaiming PV wrongly. ([#67062](https://github.com/kubernetes/kubernetes/pull/67062), [@cofyc](https://github.com/cofyc))

- Fix a bug where events/v1 Events with similar event type and reporting instance were not aggregated by client-go. ([#112365](https://github.com/kubernetes/kubernetes/pull/112365), [@dgrisonnet](https://github.com/dgrisonnet)) [SIG API Machinery and Instrumentation]

- kube-scheduler

  - Migrate scheduler to use v1beta1 Event API. any tool targeting scheduler events needs to use v1beta1 Event API ([#78447](https://github.com/kubernetes/kubernetes/pull/78447), [@yastij](https://github.com/yastij))

- kubeadm

- When `SchedulerQueueingHint` is enabled,
  the scheduler's in-tree plugins now subscribe to specific node events to decide whether to requeue Pods.
  This allows the scheduler to handle cluster events faster with less memory.

  Specific node events include updates to taints, tolerations or allocatable.

  - The `export` query parameter for list API calls, deprecated since v1.14, will be removed in v1.18.
  - The `series.state` field in the events.k8s.io/v1beta1 Event API is deprecated and will be removed in v1.18 ([#75987](https://github.com/kubernetes/kubernetes/pull/75987), [@yastij](https://github.com/yastij))

- kubeadm

- `client-go` event library allows customizing spam filtering function. 
  It is now possible to override `SpamKeyFunc`, which is used by event filtering to detect spam in the events. ([#103918](https://github.com/kubernetes/kubernetes/pull/103918), [@olagacek](https://github.com/olagacek))
- `client-go`, using log level 9, traces the following events of a HTTP request:
      - DNS lookup
      - TCP dialing

- `kubectl` will not print events if `--show-events=false` argument is passed to
  describe PVC subcommand. ([#120380](https://github.com/kubernetes/kubernetes/pull/120380), [@MaGaroo](https://github.com/MaGaroo))
- `scheduler`: Fixed missing field `apiVersion` from events reported by the taint

- Disable watchcache for events.k8.io/Event resource for compatibility with core/Event. ([#96117](https://github.com/kubernetes/kubernetes/pull/96117), [@wojtek-t](https://github.com/wojtek-t)) [SIG Scalability]