[Elie1996]

Under OnPlayerCommandText Change the return Value

Example:

pawn Код:

public OnPlayerCommandText(playerid, cmdtext[])
{
 // YOUR COMMANDS UP HERE

return 0; // --> Change return 0 with --> return SendClientMessage(playerid, "Server: Command Doesn't exist!", COLOR);
}

You can change "ServerL Command Doesn't exist!" with whatever error message you want, and you're done