My answer: 1. Pause or isolate the problematic process/workflow if possible 2. Study the logs and relevant data 3. Try to reproduce locally (in a sandbox) 4. Try to reproduce in staging environment 5. Add and deploy fix, enable the process/workflow back 6. Follow up with affected customers via support
I generally focused my answers on the success of the team and company at large. Centered on the idea that putting employees, even difficult ones, in situations where they were set up to succeed, vs fail, was key. If there were still issues, then I was very matter-of-fact with my own philosophy of not hiring a-holes, and that sometimes the talent did not justify the personality.
Clients disgruntled because their were errors on their ads. sometimes it's the publishers fault, but many times it can be the clients error. I always remain calm, let the person speak, really listen, and then they usually calm down. At that point I assure them that we'll make it right. I explain that I will research the situation to find the best possible solution. I make them feel valued and treat their situation as top priority.