diff --git a/src/app/shared/websocket-backend.service.ts b/src/app/shared/websocket-backend.service.ts
index 43641b1db049bb097e11a312bbad3e45e2b94d41..f44e0254e4f53ae5e694335b79e2abc740acb19d 100644
--- a/src/app/shared/websocket-backend.service.ts
+++ b/src/app/shared/websocket-backend.service.ts
@@ -88,6 +88,8 @@ export abstract class WebsocketBackendService<T> extends WebsocketService implem
         clearTimeout(this.pollingTimeoutId);
         this.pollingTimeoutId = null;
     }
+
+    this.data$ = null;
   }
 
   private scheduleNextPoll(): void {
diff --git a/src/app/shared/websocket.service.ts b/src/app/shared/websocket.service.ts
index f17d74f4c354fbae9db7763cec8caf619723d495..e7426d32eaacf91987f0cbbf622cfaab699da4c1 100644
--- a/src/app/shared/websocket.service.ts
+++ b/src/app/shared/websocket.service.ts
@@ -63,8 +63,10 @@ export class WebsocketService {
   protected closeConnection(): void {
     this.wsConnected$.next(false);
     this.wsSubscription.unsubscribe();
-    this.wsSubject$.complete();
-    this.wsSubject$ = null;
+    if (this.wsSubject$) {
+      this.wsSubject$.complete();
+      this.wsSubject$ = null;
+    }
   }
 
   public send(event: string, data: any) {