I just went onto the American Express web site to buy something using my points. The shopping experience was great, right up until I tried to complete my purchase. Then I got a screen that looked like this:

Really helpful, guys. Thanks.

At that point, I gave up. I’ll have to call them, taking up their time and mine.

When you build a shopping site, make sure your error messages make sense. That will immediately vault you into the top 5% of all web sites.