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macOS Sequoia 15.3 Update Fixes Third-Party Bootable Backups Failures

macOS Sequoia 15.3 Update Fixes Third-Party Bootable Backups Failures

Apple released macOS Sequoia 15.3 last week, and the new update appears to include a remedy for a bug that prevented third-party backup utilities, like SuperDuper from creating bootable backups, according to SuperDuper developer Dave Nanian.

The fix offers a remedy for an issue that reared its ugly head with the release of macOS Sequoia 15.2, which caused SuperDuper to fail in the final stages of creating a bootable backup, as the app received a “Resource Busy” error that prevented copying system preboot and recovery files.

Nanian said that macOS Sequoia 15.2 changed a feature called the Replicator, causing his app to be unable to create a bootable backup.

“macOS 15.2 was released a few days ago, with a surprise. A terrible, awful surprise,” he had wrritten 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.”

Any backup that was meant to create a bootable copy of a user’s macOS system, would fail during the final stages of the backup.

Nanian’s most recent Shirt Pocket Watch blog post is a much happier one.

Just a quick post: macOS 15.3 is now out, and with it, a fix for the broken replicator.

As such, macOS copying will work again with Erase, then copy backups. No update to SuperDuper is necessary (but feel free to install our v3.10 Beta 2, below).

Note that this does not mean boot from the copy will work in all situations (but, again, we have no control over that). But at least the copy can be made without (this) failure occurring.

Thanks for your patience as we waited for the fix from Apple. I know I’m relieved that I (hopefully) will no longer be bombarded with support because of it!

Nanian’s warning that boot from the copy won’t work in all situations is due to changes Apple made in macOS and recent Mac hardware in the name of enhancing security.

As pointed out by MacRumors, Apple Silicon Macs require the internal SSD to remain functional for external booting to work, which means a Mac with a failed internal drive will not be able to boot from a SuperDuper backup, even if the backup itself is intact.