You will get an error if Flash Fill cannot find the pattern. The first thing to check is that you're using Flash Fill close to the source data (e.g., in the adjacent cell). For instance, it won't work ...

First, set up a model cell with the replacement formatting. Next, press Ctrl+H to launch the Find and Replace dialog. There, define both the Find What and Replace With formatting by clicking "Choose ...

Excel formulas are a powerful way to quickly manipulate and display the data in your spreadsheets to your exact specifications. Once you've created an effective formula for your data, you may want to ...