An ISO works, but a direct USB installer is better. Use the same createinstallmedia command but point to a USB drive (e.g., /Volumes/MyUSB) instead of a DMG.
Avoid random ISO sites
Many “El Capitan ISO” downloads on forums, torrents, or file-sharing sites contain malware, modified kernels, or adware bundles. If a site asks you to disable SIP or install a profile — run.
Once you have the Install OS X El Capitan.app (located in your /Applications folder), follow these steps to create a bootable ISO file suitable for virtual machines or USB drives. Mac Os X 10.11 El Capitan Iso Download
Error 1: “This copy of the Install OS X El Capitan application is damaged…”
Error 2: “createinstallmedia: command not found” An ISO works, but a direct USB installer is better
Error 3: “Operation not permitted” in Terminal
Error 4: Download from App Store fails with “The requested version of macOS is not available” Avoid random ISO sites Many “El Capitan ISO”
mv ~/Desktop/ElCapitan.iso.cdr ~/Desktop/ElCapitan.iso
You now have a legitimate, working Mac OS X 10.11 El Capitan ISO file on your Desktop. The file size will be approximately 6.5 GB.
If you search Google for "Mac OS X 10.11 El Capitan ISO download", you will find dozens of sites offering direct ISO files. Most of these are dangerous. Here is why:
The Golden Rule: Never download a pre-made ISO file from a non-Apple source. Instead, download the official Install OS X El Capitan.app from Apple (or a trusted source) and create your own ISO. This guarantees integrity.
hdiutil attach /tmp/ElCapitan.dmg -noverify -mountpoint /Volumes/ElCap
Open Terminal ( /Applications/Utilities/Terminal.app ).