Recently my manager and I made a big mistake in the university library catalogue. All the library stock was not available during the summer due to refurbishment. We were tasked with showing this on the catalogue but got it a bit wrong. We set everything to Reference Only. Permanently. We had to get the whole catalogue rolled back to an earlier archived version and it took weeks to sort it out then redo everything that had been done in the interim. It was a nightmare and when I discovered it, I had such a horrible sinking feeling. To be fair to my managers, they were quite ok about it.

What’s the worst thing that you’ve done at work?