A user with the User administrator role attempts to invite an external partner who signs in with a Microsoft account (user1@outlook.com) and receives the error: "Unable to invite user user1@outlook.com Generic authorization exception." What change allows the User administrator to invite the external partner?

The correct answer is to modify the External collaboration settings from the Users blade. This is because the error "Generic authorization exception" when inviting an external user often indicates that the current external collaboration settings in Azure AD are too restrictive or misconfigured, preventing the invitation of users from specific domains or identity providers. Adjusting these settings allows the User administrator to permit invitations to Microsoft accounts. Assigning the Security administrator role to Admin1 is incorrect because the User administrator role already has permissions to invite guest users. Adding an identity provider from the Organizational relationships blade is incorrect as Microsoft accounts are already a recognized identity provider. Adding a custom domain from the Custom domain names blade is irrelevant to inviting external users with Microsoft accounts.