Just the names

The mistake

A sort is applied to a single column of a spreadsheet instead of to the whole row range, so every product name is reordered while the price column stays in its original order. Each name now sits against an unrelated price, and because a live system reads the sheet as its source of truth, the wrong prices go straight out to customers. Re-sorting on a different column afterwards destroys the last recoverable mapping between names and prices — there is no undo, no version history, and no other copy of the data.