diff --git a/src/utilities/observables/Concast.ts b/src/utilities/observables/Concast.ts
index 0126650b051..bcc8e4f7b82 100644
--- a/src/utilities/observables/Concast.ts
+++ b/src/utilities/observables/Concast.ts
@@ -178,7 +178,7 @@ export class Concast<T> extends Observable<T> {
         // Delay unsubscribing from the underlying subscription slightly,
         // so that immediately subscribing another observer can keep the
         // subscription active.
-        if (sub) Promise.resolve().then(() => sub.unsubscribe());
+        if (sub) setTimeout(()=>{sub.unsubscribe()}, 0)
         this.sub = null;
         this.latest = ["error", error];
         this.reject(error);