Turning on custom errors and displaying a friendly error page is pretty much a .NET deployment basic, lol.
Love the c:\Users\lebohangmas\desktop directory path exposed. Guess you've been having an interesting last few days, hey Lebohang?? Hopefully, you don't keep all your code on the desktop - I'm guessing you probably don't even have any source/version control??
Another basic is ensuring your SQL server is setup correctly. Connection pool errors mean they couldn't have done much or any load testing at all. Which is kind of unforgiveable for a large scale public system.
Time to find out how much was paid for this, and to who.