Add note about onReady not resolving when office.js is blocked (#5418)

Author: AlexJerabek

docs/develop/initialize-add-in.md

@@ -1,7 +1,7 @@
 ---
 title: Initialize your Office Add-in
 description: Learn how to initialize your Office Add-in.
-ms.date: 08/18/2023
+ms.date: 10/16/2025
 ms.localizationpriority: medium
 ---
 
@@ -87,6 +87,9 @@ However, there are exceptions to this practice. For example, suppose you want to
 
 Another exception would be if you want a progress indicator to appear in the task pane while the add-in is loading. In this scenario, your code should call the jQuery `ready` and use its callback to render the progress indicator. Then the `Office.onReady` callback can replace the progress indicator with the final UI.
 
+> [!IMPORTANT]
+> If the Office JavaScript API library files are blocked by network filters, firewalls, or browser extensions, `Office.onReady` will never resolve.
+
 ## Initialize with Office.initialize
 
 An initialize event fires when the Office.js library is loaded and ready for user interaction. You can assign a handler to `Office.initialize` that implements your initialization logic. The following is an example that checks to see that the user's version of Excel supports all the APIs that the add-in might call.

docs/develop/loading-the-dom-and-runtime-environment.md

@@ -1,7 +1,7 @@
 ---
 title: Loading the DOM and runtime environment
 description: Load the DOM and Office Add-ins runtime environment.
-ms.date: 05/20/2023
+ms.date: 10/16/2025
 ms.localizationpriority: medium
 ---
 
@@ -30,6 +30,9 @@ The following events occur when a content or task pane add-in starts.
 
 5. The Office client application loads the runtime environment, which downloads and caches the Office JavaScript API library files from the content distribution network (CDN) server, and then calls the add-in's event handler for the [initialize](/javascript/api/office#Office_initialize_reason_) event of the [Office](/javascript/api/office) object, if a handler has been assigned to it. At this time it also checks to see if any callbacks (or chained `then()` method) have been passed (or chained) to the `Office.onReady` handler. For more information about the distinction between `Office.initialize` and `Office.onReady`, see [Initialize your add-in](initialize-add-in.md).
 
+    > [!IMPORTANT]
+    > If the Office JavaScript API library files are blocked by network filters, firewalls, or browser extensions, `Office.onReady` will never resolve.
+
 6. When the DOM and HTML body finish loading and the add-in finishes initializing, the main function of the add-in can proceed.
 
 ## Startup of an Outlook add-in