After saving and reopening, the spreadsheet is still working correctly. The field I was using to VLOOKUP was formatted as a custom field. Clearing this error (selecting all fields with the error, beginning with the first one with the error and clicking change to Number even though I didn't really want it to be! the ctrl alt f9 , is the temporary solution , going to options-formula-auto calculate is the right way, that option turned manual, because some shortcut key on being pressed by mistake turns automatic to manual Thank you for your interest in this question.Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).Can you check and make sure the data in there is all still numerical?I think I've noticed this happening for me when I threw in a value once that was "$xyz" as opposed to "xyz" (I mean xyz to be some integer, of course). I suggest you copy your formula into Notepad, then type any number into the cell.Microsoft is conducting an online survey to understand your opinion of the Technet Web site.If you choose to participate, the online survey will be presented to you when you leave the Technet Web site. When you create external references (also called links), you can control whether the external references stay up to date, and when they are updated.
Ctrl F9 not only updated the values, but fixed the problem so it didn't happen again.When the source workbook and the destination workbook are open on the same computer, links are updated automatically.When you open a destination workbook, and the source workbook is not open, you may be alerted by the Trust Bar whether to update the links.When this option is set to automatic, Excel recalculates the spreadsheet’s formulas whenever you change a cell value.This means that, if you have a formula that totals up your sales and you change one of the sales, Excel updates the total to show the correct sum.