Onboarding a Microsoft 365 Organization Fails with: service principal name is already present for the tenant

This error occurs when a service principal from a previous onboarding attempt is still present in the customer tenant.

Under normal conditions, onboarding proceeds as follows:

1. The user signs in with a device code, and a new service principal is created in the customer tenant.
2. When Connect is clicked, the onboarding process uses that service principal to obtain an authentication token, then deletes the service principal and begins onboarding the organization.

However, if an error occurs during organization onboarding (for example, the account does not have sufficient permissions, or an organization with the same domain already exists), onboarding fails after the service principal has been deleted. If a new device code is then generated and used to sign in again too soon, the onboarding process attempts to create a service principal with the same name as the one from the failed attempt. Because service principal deletion is a soft delete that takes approximately 5 to 15 minutes to complete in Azure, the name remains in the tenant even though the Azure portal no longer displays the service principal. As a result, the error occurs.