A Professor Asked AI to Fix Page Numbers. It Deleted a Year of Notes
In short
- University of Chicago law professor William Baude says Claude deleted a year of his lecture notes and his current syllabus while he was at lunch.
- He asked it to fix page numbers. He got all files back from Dropbox. The cause is unclear, and no Anthropic statement has been reported.
- The money angle: a cloud backup costs a few euros a month. Rebuilding a year of work costs thousands.
He asked an AI to fix page numbers. It deleted the notes. A professor posted it on X on November 5, and Dexerto covered it on November 7. The lesson is boring and very useful.
What happened
William Baude teaches law at the University of Chicago. He asked Claude to update page numbers in old constitutional law lecture notes. Then he went to lunch.
When he came back, a year’s worth of lecture notes and his current-term syllabus were gone. In a screenshot, Claude’s message said the deletion was accidental. It apologised, said it had found an incorrect page reference but had not edited the notes, and asked whether he could restore the files from Dropbox.
He could. Everything came back.
What we do not know: Dexerto does not say which Claude product or model he used. The exact cause is unclear. No Anthropic statement is included. So this is one user’s account, not a confirmed bug.
How to use it
Whatever the cause, the protection is the same. Do this before you give any AI agent access to files:
- Back up first. Cloud sync with version history, or a plain copy of the folder. Baude was saved by Dropbox.
- Work on a copy. Give the agent a duplicate folder for risky edits, not your only original.
- Keep a task small and checkable. Do not walk away from a task that can delete files. Page numbers should not touch deletion at all.
- Limit permissions. If the tool lets you choose, give read access plus write to one folder, not the whole drive.
- Test your restore. A backup you never restored is a hope, not a backup.
Do the math: a year of lecture preparation, say 100 hours at €30 an hour (my assumption), is €3,000 of work. A cloud backup plan at around €10 a month is €120 a year. That is 4% of the loss, for protection against all kinds of accidents, not only AI ones.
What it means
AI tools are moving from chat to doing things on your computer. That is where the money is, and where the risk is. A bad answer in a chat costs you a minute. A bad action on your files can cost you a year.
Do not read this as a reason to avoid agents. One incident, no confirmed cause, full recovery. Read it as a reason to build the safety net before you need it. Businesses that run agents on real data should treat backups and permissions as part of the setup, not an extra.
Ivan’s Take
This is not a story about a bad AI. It is a story about a good backup. I run agents on real business data, and I would never let one touch files that exist in only one place. Set up versioned backups today. It takes ten minutes and it is the cheapest insurance you will ever buy.
Source: Dexerto
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