What must you do to troubleshoot access denied errors with BigQuery datasets protected by VPC Service Controls?

To effectively troubleshoot access denied errors with BigQuery datasets protected by VPC Service Controls, it's essential to ensure that the host project containing the Shared VPC is included in the service perimeter. VPC Service Controls create a security boundary around Google Cloud resources, and if the host project is not part of that perimeter, access to those resources can be restricted, resulting in access denied errors.

Including the host project in the service perimeter allows the necessary communication and access between the resources residing within that project and the services protected by VPC Service Controls. This ensures that users and services attempting to interact with the BigQuery datasets have the appropriate permissions and can authenticate correctly, thereby resolving the access denied issue.

In contrast, other approaches, such as increasing the dataset's access level, enabling public access, or reconfiguring firewall settings, do not address the fundamental problem, which is the configuration of the service perimeter itself. These actions could lead to broader access risks or fail to resolve issues stemming from the border established by the VPC Service Controls.