On one of the project that I was a part of, there came about an issue with air dams not being compatible with our new server racks. Air dams are used to restrict air flow from underneath the rack and we had made a “universal” one that was to be compactible on all of our products. Our customers made it clear that all racks shipped to them had to have these packaged with them. On the newest server rack we were designing, the mounting hole pattern changed slightly because of some feedback we got from our customer. This caused the air dams to not be able to fit up on the new rack. No one thought of how this would affect the air dams since everyone always just assumed that we had a design for them in place. Well the day finally came where it was discovered that the “universal” design didn’t work, which caused delays in shipping the product, because now we had to make new ones and also had to wait for our vendors to manufacture them with their lead times. My company got so used to having them ready that we got careless when a situation came about like this, where we got a wakeup call to always double check if all existing accessories are compatible with new products.