Package Big Sur installer with Composer issue

Contributor III


I downloaded and got the Big Sur installer which is 12.21 GB.
When I try to package it with Composer, the pkg is only 15.6MB and damaged.

I tried with Composer versions 10.25.1 and 10.26 beta.

Do you have the same problem ?

Thank you for your help


Contributor III

Ok, sorry. I have the answer :

Signed system volume
macOS Big Sur introduces a cryptographically signed system volume to protect against malicious tampering, which replaces the separate system volume introduced in macOS 10.15.
For IT admins, this new volume makes for a very large macOS Installer file that native macOS tools or Jamf Composer can’t build as a .pkg file, which is the most common method to deliver macOS applications. If you have Jamf or are using Jamf Composer to package the macOS Big Sur Installer to deliver via a policy, choose the option to “Create as DMG” instead of a .pkg file. macOS Big Sur’s signed system volume (SSV) raises protection of key system files beyond the reach of all current malware and should withstand the most determined attacker from altering them after the OS has booted. It also guards against inadvertent corruption and guarantees system integrity.

View solution in original post


New Contributor III

What if we use the full installer from Apple, which gives you a .pkg file?

Mr Macintosh has full database of all macOS Big Sur Beta and Final installers here >

Esteemed Contributor II

What @arnoldtaw said. Don't re-build a .pkg to deploy Install macOS Big that Apple is already creating for you. Just find the appropriate version of InstallAssistant.pkg on

New Contributor II

This script pulls it down directly and you can choose the version. then just upload to jamf and use as you want.

Contributor II

Thanks for this post. Composer package .pkg file was failing with stated error message. Simply altered to create as a .dmg file and it worked fine. This was for a SecureTest testing software that is "universal".