Provide Useful Error Messages

In the event that something on your site goes wrong, you should present an error message to the user that looks professional, is helpful, and ideally provides advice (try again later, call our support line, etc…). TicketMaster hasn’t figured that out yet:

is what I see after I tried to buy some tickets. Here are the issues with this:

• The error page isn’t styled at all. There’s no navigation, branding, etc.. It looks like amateur hour.
• The error message/reference number aren’t helpful at all.
• I have no idea if my credit card was charged, or my order was placed.
• I have no idea what I should do next. Do I hit the back button? Do I try again? Do I call them?

All in all, this is one of the worst error pages I’ve seen.