Adds the specified users to the specified roles.
Assembly: System.Web (in System.Web.dll)
One of the roles in roleNames is a null reference (Nothing in Visual Basic).
One of the users in usernames is a null reference (Nothing in Visual Basic).
One of the roles in roleNames is an empty string or contains a comma (,).
One of the users in usernames is an empty string or contains a comma (,).
roleNames contains a duplicate element.
usernames contains a duplicate element.
Role management is not enabled.
The method calls the default role provider to associate the specified users with the specified roles at the data source.
If your application uses the SqlRoleProvider class, the database updates that are performed during the call to the AddUsersToRoles method are made within a transaction. If an error is encountered, such as a user name that is already in a specified role, the transaction is rolled back and no updates are performed.
User names and role names cannot contain commas.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.