We have developed a ReactJS based Excel Web Add-in. We are rolling out the add-in using MS 365 Admin Center. The steps that have worked for our Admin Center as per our IT (Office 365 E1/E3/E5 Subscription) are:
- Sign in to Microsoft 365 Admin Center as a Global Administrator.
- Navigate to Settings => Integrated apps => Add-ins => Deploy Add-in.
- Select Upload from file, then browse and upload manifest.xml for our add-in.
- Assign to Everyone (or to specific users/groups, as per requirement)
- Review and Deploy. The add-in appears under Integrated apps after deployment.
- When users open Excel next time, they should see the add-in available there (can take a little time)
However, for one of our customers (Microsoft 365 Business Premium Subscription), the steps aren't working: First, there is no "Add-ins" under Settings => Integrated apps. Second, there is a "Upload custom apps" button. Clicking that opens a dialog that asks for App type (Office Add-in) and to upload manifest file. However uploading the manifest from there fails (Upload failed. Please check the manifest file and try again).
Note that the EXACT same manifest.xml file works for our tenant.
Taking some help from AI, I got to know that this may be due to different set of validation rules applied on different types of Office subscriptions (SKU). However, I am not sure which validation is failing here and how do I fix those.
Customer has also shared another screenshot that shows validation failed with a GUID: fda5eb4a-9e00-4fea-9148-69c3079bd3ec, but this also doesn't provide us any clue about fixing the issue.