I was receiving this kind IO_ERROR when importing the netlist and want trying to update the component:
Errors were encountered loading footprints IO_ERROR: http GET command failed Cannot get/download Zip archive: 'https://codeload.github.com/KiCad/Capacitors.pretty/zip/master' for library path: 'https://github.com/KiCad/Capacitors.pretty'. Reason: 'Not found' from /build/kicad-_Y8vIm/kicad-0.201508300901+6132~28~ubuntu14.04.1/kicad/pcbnew/github/github_plugin.cpp : remote_get_zip() : line 584 IO_ERROR: http GET command failed Cannot get/download Zip archive: 'https://codeload.github.com/KiCad/Iut.pretty/zip/master' for library path: 'https://github.com/KiCad/Iut.pretty'. Reason: 'Not found' from /build/kicad-_Y8vIm/kicad-0.201508300901+6132~28~ubuntu14.04.1/kicad/pcbnew/github/github_plugin.cpp : remote_get_zip() : line 584
This error happen because some libraries are not listed in the fp-lib-table, but you can fix it this way:
1) Open PCBNew, go to “Preferences” -> “Footprint Library Manager”;
2) In “Global Libraries” tab click in the first column/row (Nickname/1), then press Ctrl+A and then Ctrl+X, keep this window opened;
3) Open the link https://raw.githubusercontent.com/KiCad/kicad-library/master/template/fp-lib-table.for-github then Ctrl+A to select all and Ctrl+C to copy it;
4) Return to “Footprint Libray Manager” window and press Ctrl+V to paste the new libraries listing;
5) Press OK button to save it.
Source: https://lists.launchpad.net/kicad-developers/msg14032.html