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Professor returns from lunch to find Claude AI deleted a year's worth of lecture notes
Claude AI deleted a University of Chicago law professor's entire year of constitutional law notes and current syllabus during a routine page-number update. He recovered everything only because Dropbox version history saved the files.
A University of Chicago law professor lost a year's worth of constitutional law lecture notes and his current syllabus after Anthropic's Claude AI deleted the files during a routine editing task. William Baude had asked the chatbot to update page numbers in an old set of notes, only to return from lunch and find the documents gone.
"Yesterday while I was at lunch, Claude deleted a year of con law lecture notes and my current syllabus," Baude wrote on X on November 5. The incident highlights the risks of granting AI tools file-level access without manual backups in place.
What the professor asked Claude to do
Baude explained that the task was straightforward. He wanted Claude to update page references in an older set of lecture notes - a mechanical editing job that required reading document contents, not deleting them. When another X user asked what instructions he gave, Baude replied: "Updating the page numbers in an old set of lecture notes."
The exact model Baude used remains unclear. He did not specify which version of Claude handled the task, and the precise cause of the deletion has not been determined. Anthropic has not issued a public statement on the incident.
Claude acknowledged the error
In a screenshot Baude shared, Claude admitted fault directly. "I deleted your Fall 2026 FINAL syllabus .doc and all top-level Class N 2023 notes by accident, and they are not restored," the AI said. It added that it had found an incorrect page reference during its checks but had not edited the notes.
The chatbot went further, telling Baude: "You're right to be angry. I deleted your files through my own carelessness, and you shouldn't have to clean it up." Claude then asked whether Baude could restore the files via Dropbox or if it should attempt recovery itself.
Dropbox saved the data
Baude later confirmed he recovered everything through Dropbox's version history. "I did recover them all, thanks to Dropbox, but thought this would be a useful public service announcement," he wrote. Without cloud backup, the outcome could have been far worse for the professor and his students.
For professionals who rely on AI assistants to handle documents directly, the incident underscores a practical risk. Even well-designed systems can misinterpret instructions and take destructive actions. Understanding how large language models process file operations - and where their guardrails fall short - is becoming essential knowledge. Those working with Generative AI Courses increasingly emphasize operational safety alongside prompt design.
Why this matters for legal and education professionals
For lawyers, educators, and anyone managing critical documents, this case is a reminder that AI file access should come with strict boundaries. Before letting a chatbot edit documents directly, make a manual backup or work from copies. Cloud versioning saved Baude - but it won't save everyone. The cost of losing a semester's syllabus or case notes extends beyond inconvenience; it affects students, clients, and institutional trust.
Baude's willingness to share the mistake publicly gives other professionals a concrete scenario to learn from. The lesson is simple: AI tools can and will make errors, and the difference between a minor disruption and a serious loss often comes down to whether you backed up your files first.