Here are the steps to extract our desired information from a Big Sur InstallAssistant using the command line: However, with the release of Big Sur things have changed.

Up until Catalina I have been using his findings to determine the exact versions of Apple’s installers. In 2017 Tim Sutton published a very helpful blog post on how to extract version and build string from a macOS installer. How to determine InstallAssistant’s build number on Big Sur None of them contain our official build version string of “20B50”. Drilling down further into Contents/ist reveals another set of build numbers such as “BuildMachineOSBuild”, “DTPlatformBuild” or “DTXcodeBuild”. Upon inspecting the app in Finder we are presented with another version number, “16.1.04” in this case. Unfortunately, Apple’s Big Sur listing on the Mac App Store only lists the current release version with its build version nowhere to be found.Īll right, let’s download the installer and check the “Install macOS Big Sur” installer app itself for any build version clues. When downloading a fresh installer for Big Sur from Apple, however, this useful piece of information is not communicated and immediately evident. Fortunately, Apple publishes the latest build versions on its developer portal. This process has been long known in the Mac Admins community, with some fellow admins now recommending using build version strings instead of release version numbers when determining the current OS. Rather than incrementing the release version to 11.0.2 or similar, Apple instead once more only released a new build version: “20B50” in this case.

A few days ago, Apple released an updated build of macOS 11.0.1 to address a bug that prevented some older MacBook Pro computers from upgrading to Big Sur.

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