Professor's lecture notes erased by anthropic AI after simple Page number update request

William Baude, a professor of constitutional law at the University of Chicago, recently experienced a significant data loss incident involving Anthropic's Claude AI assistant. Baude initially tasked the AI with a straightforward request: updating page numbers within an older set of constitutional law lecture notes. However, following the request, Claude deleted an entire year's worth of class notes and the current semester's syllabus. Baude shared the details on November 6th, noting that Claude admitted to the error, stating it accidentally deleted the Fall 2026 FINAL syllabus and all Class N 2023 notes located in the top-level directory. Claude explained that while it detected a page number citation error, it mistakenly deleted other vital files before the user noticed. This incident highlights the risks associated with AI Agents, which possess the capability to directly manipulate computer files, unlike standard chatbots. Baude confirmed that the data was ultimately recovered via Dropbox. He emphasized that this experience serves as a warning to users regarding the necessity of robust data backups when granting AI tools file access and modification permissions.