Excel will not accept a formula that looks correct
A formula copied from a website is rejected outright, with no error in a cell, just a refusal to accept the entry. Almost always the argument separator does not match the machine.
Why it happens
Excel uses either a comma or a semicolon between arguments, decided by the language settings of the computer rather than by the file. Most English installations use commas; much of Europe uses semicolons.
A formula written with the wrong one is not wrong in any deep sense, so Excel cannot correct it. It simply refuses the entry, which reads as the formula being broken.
Function names are translated too. A German Excel expects SUMMEWENNS rather than SUMIFS, and refuses the English name the same way.
The Fixer above converts both: paste a formula in either form and it comes back in the one your Excel is set to use.
Questions
How do I know which one my Excel wants?
Type =SUM(1,1) into a cell. If it is rejected, your Excel wants a semicolon.
Can I change the setting?
Yes, under File, Options, Advanced, by turning off "Use system separators". Changing it affects every file you open, so it is worth thinking about first.
Will the file break for a colleague abroad?
No. Excel stores formulas in a neutral form and shows each person the separator their machine expects. Only typing and pasting are affected.
Set by your computer's language, not by the file. A frequent cause of a correct-looking formula being rejected.
Excel version
XLOOKUP, IFS, TEXTBEFORE and TEXTJOIN need Microsoft 365 or 2021; older versions return #NAME? instead. Choosing the older one switches every walkthrough to a formula that works there.
