Excel doesn't recognize text in the formula — usually a typo in a function or name.
Fix this with AI#NAME? appears when Excel can't interpret a name — a misspelled function, a missing quote around text, or an undefined named range.
Check the spelling
Use the formula autocomplete to pick the correct function name.
Quote text values
Wrap any literal text in double quotes.
Define the name
Create the named range in Formulas → Name Manager.
Newer functions (XLOOKUP, TEXTSPLIT) need a recent Excel version; older versions return #NAME?.