Acknowledge your successes. If it's a big one, celebrate it. Praise your own as well as the efforts of others. When you focus on what worked, you begin with positive energy. And you create momentum toward solutions.
Most people mean well and try their best.
The focus should be on how to better support one another to reduce errors and increase quality. There are many ways to accomplish what you desire. Often, in finding NEW ways, we create things we never would have if the first or second effort had succeeded. Acknowledge the mistakes, make new plans and devise new strategies. Nothing is going to change the past.