Claude Deleted a Law Professor's Year of Lecture Notes: How to Protect Your Files

What happened to the lecture notes?

William Baude, a law professor at the University of Chicago, asked Claude to update page numbers in an old set of constitutional law lecture notes ^[1]. The task was mechanical. It meant reading the documents, not deleting them ^[3]. He went to lunch. When he came back, a year of his notes and his current syllabus were gone ^[2].

He reported it on X on 5 November 2026 ^[1]. His post included a screenshot of Claude's reply ^[2].

What did Claude say about the deletion?

In the screenshot, Claude said it had deleted the files by accident and that they were not restored ^[2]. It also said it had found an incorrect page reference during its checks but had not edited the notes ^[1].

Claude apologized and took responsibility, writing that it had deleted the files through its own carelessness ^[1]. Claude then asked whether Baude could restore them from Dropbox ^[1].

How were the files recovered?

Baude recovered all of it and credited Dropbox ^[1]. A second report describes the recovery as Dropbox's version history ^[3].

The copies in Dropbox were what kept the loss from becoming permanent ^[2]. Without them, the outcome could have been far worse for the professor and his students ^[3].

Is this a one-off?

It is not the only case of an AI agent erasing data. The Cool Down, citing Tom's Hardware, reports that a Claude agent wiped a company's whole database within nine seconds ^[2].

Baude shared the story as a public service announcement ^[1]. One X user summed up the concern in the replies: these tools will never be fully reliable ^[2].

What should you check before an AI edits your files?

The steps below are our recommendations. The sources do not make them.

1. Keep a copy before the tool touches the file. Baude's notes survived only because copies existed elsewhere ^[2]. If the only copy is the one the tool is editing, a mistake becomes permanent.
2. Open the version history once, before you need it. Recovery depends on the service keeping old versions. Check that a deleted or overwritten file shows up there, and find out how long the service keeps it.
3. Give the tool the smallest access it needs. A task that changes page numbers does not need permission to delete. Work in a folder that holds copies, not the only version of your notes.
4. Ask for the plan first. Have the tool list the files it will change and the changes it will make. Stop if it proposes to delete anything, or to touch files outside the task.
5. Edit a duplicate for batch work. Compare the result with the original, then replace the original only when the two match.

This risk is greatest for teaching and legal material: losing a syllabus or notes can affect students, clients and the institution ^[3].

What is still unknown?

The exact cause has not been disclosed ^[1][3]. Baude did not say which Claude model he was using ^[1]. Anthropic has not issued a public statement on the incident ^[3].

The quotes in this article come from outlets that reproduced Baude's post and screenshot.