I am a postdoc who was supposed to co-supervise a PhD student along with another academic who invited me for that. However, I ended up fully supervising the student after the supervisor became too busy to attend meetings. Eventually, I also ended up defining a problem for the student, which, after 2 months of work, we discovered it is invalid. How should I deal with this situation? I feel that it’s my fault and feel bad for the student. The student is in his first year, and this is his first research problem.
Any ideas on this from experienced supervisors over here? Thank you.