Today I saw this: (click for full size)
Yes, it's a stack trace caused by a SQL deadlock.
What's note worthy is that this is on a live, public facing website. - for shame :(
Now how do I report this error?
Are you a Windows Phone, Nokia-X (Android) or Asha developer? If so, you could be getting rewards for the apps you build and the success they achieve by joining the DVLUP program.