Well, this is kind of a mess.
The developer of the SuperDuper! utility has pointed out a potential bug in macOS Sequoia 15.2 that may have disabled how the app can create bootable backups, and has cited that this may not be an accident. Following several years of Apple taking steps to make it harder for users to create their own external boot drives, per developer Dave Nanian, Apple may have inadvertently taken this a step further.
Nanian is the developer of backup app SuperDuper! and says that since macOS Sequoia 15.2 has changed a feature called the Replicator, his app has been unable to create a bootable backup. “macOS 15.2 was released a few days ago, with a surprise. A terrible, awful surprise,” he wrote in a blog post. “Apple broke the replicator. Towards the end of replicating the Data volume, seemingly when it’s about to copy either Preboot or Recovery, it fails with a Resource Busy error.” What this means is that at the last moment, a backup that is meant to create a bootable copy of a user’s macOS system, will fail.
Nanian added that “Since Apple took away the ability for 3rd parties (eg, us) to copy the OS, and took on the responsibility themselves, it’s been up to them to ensure this functionality continues to work, and in that, they’ve failed in macOs 15.2. Because this is their code, and we’re forced to rely on it to copy the OS, OS copying will not work until they fix it.”
Apple’s Time Machine feature is so far reported to be working correctly. Other backup utilities, such as Carbon Copy Cloner, seem to have stepped away from offering full, bootable backups. For its part, Carbon Copy Cloner, for instance, says it can only make a “best effort” to create a bootable backup for specific use cases like migrating between Intel Macs. Otherwise, the company explicitly says it does not support making a bootable drive as part of a regular backup strategy. As of 2021, Carbon Copy Cloner offered a feature that made bootable backups, albeit the founder said those days were limited because of the direction Apple was taking macOS. Apple Silicon uses a Signed System Volume and if that is damaged, reportedly a Mac won’t start up — perhaps even if the user had an external boot drive.
Stay tuned for additional details as they become available.
Via AppleInsider and Shirt Pocket Watch