I’m developing an Outlook web addin for Microsoft 365 accounts following Microsoft documents that consists of manifest.xml, webpack.config.js etc. It has:

• a button we can click to display a taskpane

• an Event based action to display a sentence in infobar automatically triggered by “OnMessageCompose”

When I sideload by running npm on localhost, both the button and that Event based action to show infobar work well, on both Outlook application and Outlook on web.

When Admin deployed (we just replaced localhost by remote url in manifest.xml), the button still work well.

But for that Event based action:

• now in Outlook application, upon composing an email, infobar is not displayed, and it displays a taskpane saying:

ADD_IN ERROR

We can’t start this add-in because it isn’t set up properly.

• in Outlook on web, infobar is not displayed, and it shows no error.

Since the addin is now hosted remotely, I believe we can not debug in VS Code any more.

I tried to debug in Outlook on web (chrome) by pressing F12. Under Network tab it does show it successfully downloaded that javascript file successfully. However under the Source tab it does not show that javascript file at all. Under the domain hosting this addin it only showed the assets/ folder. So I don’t know how to debug now.

What is the problem? And how I should debug?

Thanks.