diff --git a/src/core/classes/application-init-status.ts b/src/core/classes/application-init-status.ts
index f98420f81..8cfe10e86 100644
--- a/src/core/classes/application-init-status.ts
+++ b/src/core/classes/application-init-status.ts
@@ -24,4 +24,9 @@ export class CoreApplicationInitStatus extends ApplicationInitStatus {
         super(injector.get(APP_INITIALIZER, []));
     }
 
+    whenDone(callback: () => unknown): void {
+        // eslint-disable-next-line promise/catch-or-return, promise/no-callback-in-promise
+        this.donePromise.then(callback);
+    }
+
 }
diff --git a/src/core/services/filepool.ts b/src/core/services/filepool.ts
index 275785a4a..042558991 100644
--- a/src/core/services/filepool.ts
+++ b/src/core/services/filepool.ts
@@ -102,17 +102,15 @@ export class CoreFilepoolProvider {
     /**
      * Initialize queue.
      */
-    async initialize(): Promise<void> {
-        // Waiting for the app to be ready to start processing the queue.
-        await ApplicationInit.donePromise;
+    initialize(): void {
+        // Start processing the queue once the app is ready.
+        ApplicationInit.whenDone(() => {
+            this.checkQueueProcessing();
 
-        this.checkQueueProcessing();
-
-        // Start queue when device goes online.
-        Network.onConnect().subscribe(() => {
-            // Execute the callback in the Angular zone, so change detection doesn't stop working.
-            NgZone.run(() => {
-                this.checkQueueProcessing();
+            // Start queue when device goes online.
+            Network.onConnect().subscribe(() => {
+                // Execute the callback in the Angular zone, so change detection doesn't stop working.
+                NgZone.run(() => this.checkQueueProcessing());
             });
         });
     }
diff --git a/src/core/services/lang.ts b/src/core/services/lang.ts
index c14cd0054..b3eee335e 100644
--- a/src/core/services/lang.ts
+++ b/src/core/services/lang.ts
@@ -50,7 +50,7 @@ export class CoreLangProvider {
             document.documentElement.setAttribute('dir', dir);
         });
 
-        await this.initializeCurrentLanguage();
+        this.initializeCurrentLanguage();
     }
 
     /**
diff --git a/src/core/singletons/index.ts b/src/core/singletons/index.ts
index deee2a2be..cb3a81e9a 100644
--- a/src/core/singletons/index.ts
+++ b/src/core/singletons/index.ts
@@ -57,6 +57,8 @@ import { Zip as ZipService } from '@ionic-native/zip/ngx';
 
 import { TranslateService } from '@ngx-translate/core';
 
+import { CoreApplicationInitStatus } from '@classes/application-init-status';
+
 /**
  * Injector instance used to resolve singletons.
  */
@@ -198,7 +200,7 @@ export const ModalController = makeSingleton(ModalControllerService);
 export const PopoverController = makeSingleton(PopoverControllerService);
 export const ToastController = makeSingleton(ToastControllerService);
 export const GestureController = makeSingleton(GestureControllerService);
-export const ApplicationInit = makeSingleton(ApplicationInitStatus);
+export const ApplicationInit = makeSingleton<CoreApplicationInitStatus>(ApplicationInitStatus);
 export const Application = makeSingleton(ApplicationRef);
 export const NavController = makeSingleton(NavControllerService);
 export const Router = makeSingleton(RouterService);
diff --git a/src/core/singletons/subscriptions.ts b/src/core/singletons/subscriptions.ts
index 0c66c939f..3ea609a32 100644
--- a/src/core/singletons/subscriptions.ts
+++ b/src/core/singletons/subscriptions.ts
@@ -44,7 +44,7 @@ export class CoreSubscriptions {
                 // Unsubscribe using a timeout because we can receive a value immediately.
                 setTimeout(() => subscription.unsubscribe(), 0);
 
-                onError?.call(error);
+                onError && onError(error);
             },
         );
     }