The error you getting is when the player you trying to access is not in the fort_playspace. This is often fixed by checking if the player is active. So EVERYTIME you read or write to the Data variable you should check if the player you trying to access is active by just checking player.IsActive and if it fail you should not read or write to the Data variable. I don’t really know how your code looks but in this case the UpdateValues() function is the one crashing and not OnPlayerRemoved. So you probably write or read to the Data variable in the UpdateValues() function. So make sure you check if the player is active before reading or write to the Data variable.