wpmu_validate_blog_signup

Array of domain, path, blog name, blog title, user and error messages.

• 'domain'
  (string) Domain for the site.
• 'path'
  (string) Path for the site. Used in subdirectory installations.
• 'blogname'
  (string) The unique site name (slug).
• 'blog_title'
  (string) Blog title.
• 'user'
  (string|WP_User) By default, an empty string. A user object if provided.
• 'errors'
  (WP_Error) WP_Error containing any errors found.