Cannot add addon by URL - Microsoft 365 Admin Centre

Question

Summary

A customer is trying to add an integrated custom app (add-in) and receiving an error after inputting the "custom url".

Replication steps

1. Login to https://admin.microsoft.com/Adminportal
2. Select … Show All then Settings > Integrated apps
3. Click Add-ins on the top right
4. In the new window, click Deploy add-ins
5. Click next then upload custom app
6. Select upload manifest from URL and enter the manifest.xml address and click 'next'

Result - Following error displayed

Cannot perform the action you requested. Please try again later. (510c4e02-b030-40ed-9992-2ae8832bdabf)

Things I checked/tried

• Generic error makes google search diluted.
• The error code in the message changes every time we re-try it, so unsure of it's meaning.
• The user can visit the xml url in their browser (i.e. not blocked by proxy)
• The user has the "Global Admin" role assigned in the user admin center.

Answer 1

The url needs to contain the protocol https://

Despite it already being embedded in front of the input field.

The below is the correct example of how to input this field.