Xpath error "Expression must evaluate to a node-set"

Not sure what this error means,. I get this with every xpath I try.
I basically want to extract the spanish URLs (hreflang) out of a list of websites.
I tried these:
=XPathOnUrl(A1,"//link[@hreflang='es']","href")
=XPathOnUrl(A1,"//link[starts-with(@hreflang,'es')]","href")

What am I doing wrong or what can I try ? Thanks !

Looks good to me, perhaps try and reset your Global HTTP Settings?

Just tried. Doesn´t work...

Is it the same for all input URLs?

Yes, for all

Can you email an empty workbook with only an example URL and this formula to info@seotoolsforexcel.com?