Troubleshooting Outlook add-in error with “Please sideload your add-in to see app body.”; Unable to right click for “Inspect”;

Symptom:

For our self developed Outlook add-in, with react.js and node.js, we deployed it through M365 to thousands of users. It works in most of the users device, but ~ 5 users reported that their add-in not functional for any button clicking, some with a white screen not loading any front end components; and some showing an error message “Please sideload your add-in to see app body.”

Further more, for these users, even unable to proceed a right clicking to show the menu nor further diagnose with the “Inspect” with the browser developer tool.

Solution:

Found the curial component is to install the webview2 on those users’ device.

WebView2 – Microsoft Edge Developer

After this installation, all affected users add-in works properly.

The info was obtained from MS support provided docs:

Browsers and webview controls used by Office Add-ins – Office Add-ins | Microsoft Learn

Debug Office Add-ins – Office Add-ins | Microsoft Learn