Unknown Archive type
Gallery upload error. Cannot extract archive.

K2 2.5.4
SIGPRO 2.5.6
J1.7.3
rt_Camber 1.3
Gantry 3.2.13

I tried to upload an archive.zip file with some images in it the same way I have done hundreds of times since the dawn of K2 and I get that error. What's up with that? Doesn't K2 and SIGPRO work together with J1.7.3?