I have a VBA subroutine within an excel spreadsheet which goes through
several cells containing links to external spreadsheets and changes the
formulas containing those links to point to a different spreadsheet based on
the date.

It works, kinda, except for the annoying popups which occur from trying to
link to non-existing spreadsheets. The title shows "Update Values:" with a
spreadsheet link.

I was wondering if there's a way to prevent these dialogs from showing up
when a link was changed in a formula to now point to a non-existent
spreadsheet.

The formulas contain something like "if(iserror(vlookup( referencing an
external spreadsheet)), "ND", vlookup(..))".

Come to think of it, is there a way to check if the spreadsheet exists
before even attempting a link to it in a formula and yet still keep the
formula?

--
Ken Shaffer