Change

var targetOwner = arg.Length > 1 ? ulong.Parse(arg[1]) : player.userID;

To
var targetOwner = arg.Length > 1 ? ulong.Parse(arg[1]) : (ulong)player.userID;

chuckyau

Change

var targetOwner = arg.Length > 1 ? ulong.Parse(arg[1]) : player.userID;

To
var targetOwner = arg.Length > 1 ? ulong.Parse(arg[1]) : (ulong)player.userID;

thanks! it worked

Failed to compile: Type of conditional expression cannot be determined because 'ulong' and 'BasePlayer.EncryptedValue' implicitly convert to one another | Line: 471, Pos: 39

Same here

same

Error while compiling BuildingSkins: Type of conditional expression cannot be determined because 'ulong' and 'BasePlayer.EncryptedValue<ulong>' implicitly convert to one another | Line: 471, Pos: 39

after change this

var targetOwner = arg.Length > 1 ? ulong.Parse(arg[1]) : player.userID;

To
var targetOwner = arg.Length > 1 ? ulong.Parse(arg[1]) : (ulong)player.userID;

plagin start works again 

thanks man