| Error Message | Likely Cause | Solution | |---------------|--------------|----------| | "This copy of the Install OS X El Capitan application can’t be verified" | Expired certificate | Change system date via Terminal: date 011212152015 | | "Invalid checksum" | Corrupted ISO | Re-create using the original method above | | "The disk you inserted was not readable by this computer" | Incorrect ISO format | Ensure you used UDTO conversion, not a simple DMG | | VM stucks at black screen after Apple logo | Missing VM unlocker (VMware) or wrong CPUID (VirtualBox) | Apply the CPUID fix for VirtualBox or unlocker for VMware | | "Could not find installer medium" | ISO not bootable | Use createinstallmedia method, not a simple file copy |
# Create a blank temporary disk image hdiutil create -o /tmp/ElCapitan.cdr -size 8000m -layout SPUD -fs HFS+J # Mount the blank image hdiutil attach /tmp/ElCapitan.cdr.dmg -noverify -mountpoint /Volumes/install_build # Write the installer files to the mounted image sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/install_build --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app --nointeraction # Unmount the newly created installer volume hdiutil detach /Volumes/Install\ OS\ X\ El\ Capitan # Convert the DMG image into an ISO-compatible CDR format hdiutil convert /tmp/ElCapitan.cdr.dmg -format UDTO -o /tmp/ElCapitan.iso # Move the final ISO file to your desktop and rename it properly mv /tmp/ElCapitan.iso.cdr ~/Desktop/ElCapitan.iso Use code with caution. Troubleshooting Common Installation Errors macosxelcapitan10111imageiso work
– You can create a legitimate ISO yourself if you still have the Install OS X El Capitan.app file, using commands in Terminal or tools like createinstallmedia plus hdiutil . | Error Message | Likely Cause | Solution
Once the app is in your Applications folder, use these Terminal commands to build the ISO image. macosxelcapitan10111imageiso work