Hi @Shizhao, thanks for taking the time to report this!
Unfortunately this report lacks some information. If you have time and can still reproduce the problem, please add a more complete description to this report (if "the page exists" it would be good to know which exact one). Ideally, exact and clear steps to reproduce should allow any other person to follow these steps (without having to interpret those steps) and see the same results. Problems that others can reliably reproduce can get fixed faster. Thanks!