I get this message sometimes when opening a workbook. Generally I have copied a formula from another workbook instead of a value, but i always want to check before breaking things.
I used a Microsoft support article (ignored the Edge promo):
- Type CTRL+F (opens Find and Replace Window)
- Click [Options >>]
- Fill in these values
- Find What: \[
- the MS article uses [, but I got some false positives from that
- Within: Workbook
- Look in: Formulas
- Click [Find Next] to search
- On the Data tab, in the Connections group, click Edit LinksHere you can also update and break the links, but you do not see in which cells they are used.
- Click [Startup Prompt...]
- Select the option that you want