The only free and comprehensive online etymological dictionary of the Spanish language
fallar (Verb) "to fail"
From Latin fallare "to deceive," "to mistake." From Proto-Italic *faln-e/o- 'id.' From Proto-Indo-European *sgwhel-n- "to stumble."
According to Tibón (1988), fallar is the origin of the surname de Falla. He also writes that the word is not the origin of the surname de Falla found in Valencia, though he states this without further explanation.
Indo-European
Romance
Portuguese falhar, French faillir, Italian fallare
Hellenic
Ancient Greek σφάλλομαι (sphállomai) "to fall," "to be ruined"
Armenian
Armenian sxalem "to fail"
Indo-Iranian
Sanskrit skhalate "to stumble," Middle Persian škarwīdan 'id.'