A short list of the errors that trip up almost every beginner, so they're recognized instead of panicked over.
| Error | Real cause |
|---|---|
| #DIV/0! | A formula divided by an empty or zero cell |
| #REF! | A formula points at a cell that got deleted |
| #NAME? | A typo in a function name, or a missing quote around text |
| Rows scrambled after sorting | Only one column was selected before sorting, not the whole table |
It's always fixable
None of these mean the file is broken. Each has one specific, fixable cause — find the referenced cell or the exact formula and the fix is usually obvious once seen.
A circular reference happens when a formula refers back to its own cell, directly or through a chain — A1 containing =A1+1 is the simplest example. Excel can't calculate a result that depends on itself, and shows a warning rather than a wrong number.