How to force a password change programmatically in Active Dictionary

To force a user to change their password at next logon, set the pwdLastSet attribute to zero (0). To remove this requirement, set the pwdLastSet attribute to -1. The pwdLastSet attribute cannot be set to any other value except by the system.

The following C# code example shows how to set the "User must change password at next logon" option.

  var directoryEntry = new DirectoryEntry();
	try
	{
		using(directoryEntry = new DirectoryEntry(userDN))
		{
            // force password change at next logon
			directoryEntry.Properties["pwdLastSet"].Value = 0; 
			directoryEntry.CommitChanges();
		}
	}
	catch (Exception ex)
    { 
    }