Patch Catalina or Mojave macOS Installer App for Unsupported Machines

[fusion71au]

Patch Catalina or Mojave macOS Installer App for Unsupported Machines

 

Often for economic reasons, Apple prevents the Installer.app for its latest macOS from installing on older machines perfectly capable of running it eg macOS 10.14 Mojave on Unsupported Macs Thread.

 

 

In Mojave 10.14, @ASentientBot posted a method to patch the distribution file in OSInstall.mpkg to enable the Mojave installer to install on unsupported machines (with or without graphics card metal support). 

 

In Catalina 10.15beta, the above method no longer works since Apple is checking OSInstall.mpkg for its file signature and the mandatory requirement in Catalina to install to 2 separate apfs volumes necessitates using the original Catalina macOS Base System Installer.  Fortunately, it is still possible to substitute High Sierra’s Apple Signed OSInstall.mpkg inside the Catalina or Mojave InstallESD.dmg by making it R/W.

 

The procedure below will allow Macs or Hacks able to install High Sierra to also install Catalina or Mojave (eg SMBIOS MacPro5,1, iMac11,3, MacBook Pro7,1 which have been unsupported in macOS 10.14.x and 10.15beta) -credit to @ASentientBot's post.

 

Prerequisites

1. Mac or Hack capable of and running High Sierra 10.13.x

2. An original, untouched copy of OSInstall.mpkg from High Serra InstallESD.dmg - attached OSInstall_10.13.6.mpkg.zip save to your ~/Downloads folder

3. macOS Installer App eg for Catalina beta or Mojave downloaded to /Applications

4. Add NVRAM boot arg (or Clover config.plist boot arg on a hack) -no_compat_check to enable system to boot to final completed Mojave or Catalina install.

 

Procedure

1. Open Terminal and type the following

 

open /Applications/Install*/Contents/SharedSupport/InstallESD.dmg (assuming the Catalina or Mojave Installer App is in /Applications)

 

2. Open Disk Utility, click File|New Image|Image from ‘InstallESD”

Spoiler

3. Save as read/write image, no encryption in /Applications

4. Unmount InstallESD in DU by clicking the "eject" icon next to it

 

 

5. Open the R/W InstallSD.dmg in /Applications and replace Catalina’s/Mojave's OSInstall.mpkg with High Sierra’s version by typing in terminal

 

open /Applications/InstallESD.dmg
cp ~/Downloads/OSInstall_10.13.6.mpkg /Volumes/InstallESD/Packages/OSInstall.mpkg

 

6. Unmount InstallESD in DU by clicking the "eject" icon next to it

7. Replace original Catalina/Mojave InstallESD.dmg with our patched one, making a backup of the original.  In terminal, type

 

sudo mv /Applications/Install*/Contents/SharedSupport/InstallESD.dmg /Applications/InstallESD_orig.dmg
sudo mv /Applications/InstallESD.dmg /Applications/Install*/Contents/SharedSupport/

 

8.  Test the newly patched installer!…

Edited June 13, 2019 by fusion71au
Fix typos, grammar