Somewhere along the recent 7.x versions, the stack trace disappeared along with the error icon in the web player. In practice, this has been a useful and helpful feature - the user can just send the stack trace along to support and troubleshooting time is reduced. Especially when you have a server cluster accessed through a load balancer - the problem is much more quickly isolated.
Now the user gets an error message on the screen w no trace, and then the librry home page appears - does not help trpubleshooting at all,