diff --git a/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/AbstractEventSource.java b/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/AbstractEventSource.java
index eba4e7ac0a..8d9984db14 100644
--- a/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/AbstractEventSource.java
+++ b/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/AbstractEventSource.java
@@ -2,7 +2,7 @@
 
 public abstract class AbstractEventSource implements EventSource {
 
-  protected EventHandler eventHandler;
+  protected volatile EventHandler eventHandler;
 
   @Override
   public void setEventHandler(EventHandler eventHandler) {
diff --git a/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/internal/InformerEventSource.java b/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/internal/InformerEventSource.java
index d9252bb4c6..64b4a8d753 100644
--- a/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/internal/InformerEventSource.java
+++ b/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/internal/InformerEventSource.java
@@ -4,6 +4,9 @@
 import java.util.Set;
 import java.util.function.Function;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import io.fabric8.kubernetes.api.model.HasMetadata;
 import io.fabric8.kubernetes.client.KubernetesClient;
 import io.fabric8.kubernetes.client.informers.ResourceEventHandler;
@@ -16,35 +19,42 @@
 
 public class InformerEventSource<T extends HasMetadata> extends AbstractEventSource {
 
+  private static final Logger log = LoggerFactory.getLogger(InformerEventSource.class);
+
   private final SharedInformer<T> sharedInformer;
-  private final Function<T, Set<CustomResourceID>> resourceToUIDs;
+  private final Function<T, Set<CustomResourceID>> resourceToCustomResourceIDSet;
   private final Function<HasMetadata, T> associatedWith;
   private final boolean skipUpdateEventPropagationIfNoChange;
 
   public InformerEventSource(SharedInformer<T> sharedInformer,
-      Function<T, Set<CustomResourceID>> resourceToUIDs) {
-    this(sharedInformer, resourceToUIDs, null, true);
+      Function<T, Set<CustomResourceID>> resourceToCustomResourceIDSet) {
+    this(sharedInformer, resourceToCustomResourceIDSet, null, true);
   }
 
   public InformerEventSource(KubernetesClient client, Class<T> type,
-      Function<T, Set<CustomResourceID>> resourceToUIDs) {
-    this(client, type, resourceToUIDs, false);
+      Function<T, Set<CustomResourceID>> resourceToCustomResourceIDSet) {
+    this(client, type, resourceToCustomResourceIDSet, false);
   }
 
   InformerEventSource(KubernetesClient client, Class<T> type,
-      Function<T, Set<CustomResourceID>> resourceToUIDs,
+      Function<T, Set<CustomResourceID>> resourceToCustomResourceIDSet,
       boolean skipUpdateEventPropagationIfNoChange) {
-    this(client.informers().sharedIndexInformerFor(type, 0), resourceToUIDs, null,
+    this(client.informers().sharedIndexInformerFor(type, 0), resourceToCustomResourceIDSet, null,
         skipUpdateEventPropagationIfNoChange);
   }
 
   public InformerEventSource(SharedInformer<T> sharedInformer,
-      Function<T, Set<CustomResourceID>> resourceToUIDs,
+      Function<T, Set<CustomResourceID>> resourceToCustomResourceIDSet,
       Function<HasMetadata, T> associatedWith,
       boolean skipUpdateEventPropagationIfNoChange) {
     this.sharedInformer = sharedInformer;
-    this.resourceToUIDs = resourceToUIDs;
+    this.resourceToCustomResourceIDSet = resourceToCustomResourceIDSet;
     this.skipUpdateEventPropagationIfNoChange = skipUpdateEventPropagationIfNoChange;
+    if (sharedInformer.isRunning()) {
+      log.warn(
+          "Informer is already running on event source creation, this is not desirable and may " +
+              "lead to non deterministic behavior.");
+    }
 
     this.associatedWith = Objects.requireNonNullElseGet(associatedWith, () -> cr -> {
       final var metadata = cr.getMetadata();
@@ -76,13 +86,20 @@ public void onDelete(T t, boolean b) {
   }
 
   private void propagateEvent(T object) {
-    var uids = resourceToUIDs.apply(object);
+    var uids = resourceToCustomResourceIDSet.apply(object);
     if (uids.isEmpty()) {
       return;
     }
     uids.forEach(uid -> {
       Event event = new Event(CustomResourceID.fromResource(object));
-      this.eventHandler.handleEvent(event);
+      /*
+       * In fabric8 client for certain cases informers can be created on in a way that they are
+       * automatically started, what would cause a NullPointerException here, since an event might
+       * be received between creation and registration.
+       */
+      if (eventHandler != null) {
+        this.eventHandler.handleEvent(event);
+      }
     });
   }