Unable to set PR reviewer reviewer2

Unable to set all the PR reviewers, check the following usernames are correct: reviewer2

Unable to set PR reviewer not_a_collaborator

error: Reviews may only be requested from collaborators. One or more of the users or teams you specified is not a collaborator of the owner-name/repo-name repository.

Unable to set all the PR reviewers, check the following usernames are correct: not_a_collaborator

Unable to set PR reviewer not_a_collaborator

error:

Unable to set all the PR reviewers, check the following usernames are correct: not_a_collaborator

Unable to set PR reviewer not_a_collaborator

Unable to set PR reviewer reviewer