Dear Spot R&D and Maintenance Team, I am writing to report an issue with the web version of Spot.  Earlier today, I noticed that the tool fails to parse and evaluate basic LTL formulas, a typical example being p U q.  I think that this problem is not caused by timeouts or out-of-memory errors. Spot is a highly valuable and influential open-source project. Thank you sincerely for your long-term efforts and outstanding contributions to the research community. Chaofeng Yu Xidian University cfyu cfyu@stu.xidian.edu.cn