Nobody is perfect. It is good to accept and describe a circumstance where you have made a mistake that demanded a redo for a project. When a recruiter asks this question, they expect honesty from the candidate. Therefore, you must admit to your mistake instead of trying to cover it up. Interviewers seek employees who view mistakes as opportunities to learn rather than looking at them as failures. Ideally, it would help if you answered this question as follows: "Firstly, I would analyze the problem and the source and create a list of a few distinct solutions. In case none of those solutions are possible without completely redoing the project. If I felt I might miss the deadline due to such errors, I would instantly approach my supervisor and inform them about the situation. Especially if the mistake is my fault, I must be honest and open about it. It is a good growth opportunity and learning for me. Also, it will help others to prevent making the same mistakes. Eventually, I would give in extra time if required to complete the project."