The #NAME? error means Excel doesn't recognize something in your formula — usually a misspelled function name, a missing quote, or an undefined name. It's Excel saying "I don't know what this word is." Here's how to fix it.
What #NAME? means
#NAME? appears when Excel encounters text in a formula it can't interpret as a function, named range, or valid reference. Something is written that Excel doesn't recognize as a known term.
The common causes
Misspelled function name. The classic cause. =VLOKUP(...) or =SUMM(...) triggers #NAME? because those aren't real functions. Even a small typo does it.
Missing quotation marks around text. Text values in formulas need quotes. =IF(A1=East, ...) errors because Excel reads East as an undefined name; it should be =IF(A1="East", ...).
A named range that doesn't exist. If your formula references a named range (like =SUM(Sales)) but that name isn't defined — or was deleted, or is misspelled — you get #NAME?.
Missing the colon in a range. =SUM(A1 A10) errors; it needs to be =SUM(A1:A10). A missing colon makes Excel misread the range.
Using a function from a newer Excel version. If a formula uses XLOOKUP, TEXTJOIN, or another newer function and the file is opened in an older Excel that doesn't have it, that function shows as #NAME? because that version doesn't recognize it.
Text without the right function. Trying to use a function name that requires an add-in that isn't loaded.
How to fix it
Check the function spelling. Look at the formula and verify every function name is spelled correctly. Excel's autocomplete helps — start typing the function and pick it from the dropdown to guarantee correct spelling.
Check your quotes. Make sure all text values are wrapped in double quotes: "East", "Complete", "Yes". Unquoted text is the second most common cause.
Verify named ranges. Go to Formulas > Name Manager to see all defined names. Confirm the name in your formula exists there and is spelled the same way.
Look for missing colons in ranges: A1:A10, not A1 A10.
Check version compatibility. If the error involves a newer function and the file is shared, the recipient's Excel version may not support it. Use a more universally available function (INDEX/MATCH instead of XLOOKUP, for example) for shared workbooks.
The quick diagnostic
Read the formula slowly and ask: is every word either a correctly-spelled function, a defined name, or wrapped in quotes as text? The #NAME? culprit is almost always a word that's none of those three — a typo'd function, unquoted text, or a name that doesn't exist.
The takeaway
#NAME? is a recognition error: Excel found a word it doesn't understand. Check function spellings first (use autocomplete), then quotes around text, then named ranges and range colons. It's nearly always a small typo, and once you spot the unrecognized word, the fix is immediate.