Issue:  
If you are not able to create a new application or your pipelines disappeared in Spinnaker UI (refer attachment for SS), but still visible in OES UI.


Troubleshooting: 


Kindly check all the pods are up and running especially Front50 (responsible to record  for all Spinnaker metadata, including: application, pipeline and service account configurations.)pod logs


Logs of Front50 pod:


2022-01-04 17:47:11.978 ERROR 1 --- [ool-4-thread-14] c.n.s.f.m.pipeline.DefaultPipelineDAO  : Unable to refresh: {}java.lang.NullPointerException: null
    at com.netflix.spinnaker.front50.model.StorageServiceSupport.buildObjectKey(StorageServiceSupport.java:312) ~[front50-core.jar:na]
    at com.netflix.spinnaker.front50.model.StorageServiceSupport.fetchAllItems(StorageServiceSupport.java:333) ~[front50-core.jar:na]
    at com.netflix.spinnaker.front50.model.StorageServiceSupport.refresh(StorageServiceSupport.java:298) ~[front50-core.jar:na]
    at com.netflix.spinnaker.front50.model.StorageServiceSupport.lambda$startRefresh$1(StorageServiceSupport.java:146) ~[front50-core.jar:na]
    at rx.internal.util.ActionSubscriber.onNext(ActionSubscriber.java:39) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.observers.SafeSubscriber.onNext(SafeSubscriber.java:134) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeRedo$2$1.onNext(OnSubscribeRedo.java:244) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeTimerOnce$1.call(OnSubscribeTimerOnce.java:49) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.schedulers.ExecutorScheduler$ExecutorSchedulerWorker.run(ExecutorScheduler.java:107) ~[rxjava-1.3.8.jar:1.3.8]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
    
at java.base/java.lang.Thread.run(Thread.java:829) ~[na:na]


Resolution :
Restart Front50 pod, after this you should be able to create application