Across the years since it was launched I have done a lot of work with Management Reporter, including many migrations to new servers and upgrades which necessitated a migration to a new server or instance of SQL Server, but have never seen this particular error message before.
In this case, I migrated the Management Reporter database to a new server and installed the very latest version of the server software. When I started the database configuration, I received this error message:
Database configuration: The connection to the database was successful, but the connection to database 'Management Reporter' failed. Verify that the Management Reporter service account has been added to the General User role in the database.