Have you ever had an unsuccessful project and what did you learn?

I have had tasks which did not go as planned. In such situations what I did was to analyse my work together with someone senior from my team and try to realise what led to that outcome. Errors and set backs are all part of the process. Fortunately, they are the events that give you the most experience and are the best source of new knowledge. It is important to be able to accept that those kind of events will be crawling from time to time into your work life and you have to embrace them as an opportunity. Each time you are not successful with a task will give you unique insights of what and how to better in your work so to avoid it in the future.