Hello Guest If I say "it's an error on our part", I mean "it's our error". If I say "it's an error on our behalf", I mean "someone else has made an error while representing us". The second construction should in theory be very rarely heard, but in fact native speakers often confuse the two (and their variants).
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.