The goal is to make a USB installer that includes the update to 13.6 and the two big firmware updates. I'm aware of the partial installer app download issue. These instructions worked previously from a 10.12 system: https://7labs.io/tips-tricks/macos-high-sierra-direct-download.html Today... I can't get the local HTTP server part to work on a 10.12.3 system! If I do just that part on my 10.13.6 (or 10.13.4) system, the local HTTP server part works as expected. I can download those files from a directory on my Desktop per those instructions. Doing the exact same thing on the 10.12.3 system gives me: code 404, message File not found Was there a change in the terminal commands from 10.12 to 10.13? Do I need to update 10.12.3 to a newer 10.13 build for this to work? Of course I can't use the 10.13 system to download the 10.13 installer! Apple omits the download option "for my convenience" since it's already installed... I know I used a 10.12 system to make the 10.13.4 USB installer. I can't remember what build revision though now and I no longer have that same install. It's acting broken as described from 10.12.3. I'm pretty confident I've ruled out typos in the file paths. Literally cutting/pasting from the same notes - and again, this part works on the 10.13.6 system. Can anyone give a sanity check here?