Installing macOS 27: First insights and hurdles | News

For many years, the start of Apple’s developer conference has been accompanied by the release of test versions of all revised systems. This is initially limited to those users who are registered with Apple as developers, because the first beta versions usually carry the risk of serious programming errors. The developer beta of macOS is enjoying great demand because it can also be tried out without a second device – for example on an external SSD, a separate APFS volume or in a virtual machine (VM). With macOS 27 (Golden Gate), developers willing to test have somewhat greater challenges to overcome.

The test run using VM is popular for a first glance: The beta starts in a separate window parallel to the stable system and only slows down the Mac slightly. However, it seems that this variant in particular cannot be installed straight away in the first developer beta of macOS 27.0: The IPSW file available in the download area of ​​Apple’s developer portal cannot be successfully used as the basis for a virtual machine. The separate download “Device Support for macOS 27 beta”, which is supposed to add the corresponding permissions to the host system, does not help in many cases.

First Tahoe, then update
Currently, the only way to achieve success is to upgrade a Tahoe installation. To do this, registered developers must log in to a Tahoe VM with their Apple account and then switch to “macOS Golden Gate 27 Developer Beta” in the Settings app under “General/Software Update” in the “Beta Updates” tab. The update will then appear. Occasionally the installation fails with the warning “could not be personalized” – here only a second (or third) attempt helps. Anyone who hoped that the download of the new system would be narrower than previous systems will be disappointed: an update from 26 to 27 is a good 17 GB, the IPSW image is over 22 GB in size.

It is currently only possible to set up a Golden Gate VM via the detour of a Tahoe installation.

Encrypted HFS+ discontinued, new log format
Howard Oakley took a close look at Golden Gate and the release notes and discovered some interesting details. Apple has announced that access to encrypted HFS+ volumes via CoreStorage will no longer be possible in future versions of macOS – an unsurprising step after almost ten years of APFS. The recently introduced image format ASIF now receives a Swift API. In addition, the system-wide log service changes the format for archive files. It can be read by macOS 26.2 and newer.

Three years of support for Intel Macs
Rosetta, which enables macOS to use software compiled for the x86 architecture on Apple Silicon, will remain an (optional) part of macOS for another year; macOS 28 will then be over. If you still use an Intel computer with macOS Tahoe, you have to do without macOS 27 (Golden Gate). But there is also good news: Tahoe Macs with an Intel chip will continue to receive security updates for three years.