macOS Big Sur upgrade can lead to data loss without ample storage
An issue with Apple's macOS Big Sur installer allows users to upgrade from an earlier operating system without first verifying that the target Mac has enough free hard drive space, resulting in installation failure and data loss.
The problem is present in currently shipping Big Sur installers and appears to date back to the first macOS 11 builds launched in November, reports Mr. Macintosh. Interestingly, subsequent point releases and delta updates are unaffected by the bug.
Apple's installers fail to check system hard drive space on initiation and continue to run through the installation process until all storage is exhausted. The resulting failure can lead to an install loop, purgatory in Boot Recovery Assistant with a pop-up reading, "An error occurred preparing the software update," or display of Big Sur's Recovery startup screen that shows no startup disk available.
Macs require at least 35.5GB of free space -- not including the 13GB installer -- to upgrade to Big Sur.
According to the publication, any Mac that is compatible with macOS Big Sur or has downloaded the macOS Big Sur upgrade is vulnerable to the flaw. Testing has confirmed the issue exists in both macOS Big Sur 11.2 and 11.3 beta versions, and is possibly present in macOS Big Sur 11.1.
A failed installation might be the least of a potential upgrader's worries, however, as Macs with a T2 security chip can suffer data loss when FileVault 2 encryption is activated. As detailed by Mr. Macintosh, users are unable to use their Mac's admin password to initiate the recovery process. Further, attempting to reset the password using Personal Recovery Key or AppleID fails, while Target Disk Mode is rendered unusable on Catalina and Big Sur. Passwords do work in TDM on macOS Mojave and High Sierra, the report says.
Data recovery is possible using a system backup and a second Mac, though the process is complicated when FileVault is enabled. Macs that did not have FileVault enabled prior to upgrade can free up space for a new install through a bit of quick file management in Terminal or transferring data to a second Mac via TDM.
Alternatively, users who do not need to recover data from an affected Mac can simply erase the drive and reinstall macOS. Newer Macs with T2 chips require users to go through an "Erase Mac" step, according to the report.
Mr. Macintosh alerted Apple to the issue, and others have complained of identical problems on Apple's Support Forums, but the company has yet to respond.
The problem is present in currently shipping Big Sur installers and appears to date back to the first macOS 11 builds launched in November, reports Mr. Macintosh. Interestingly, subsequent point releases and delta updates are unaffected by the bug.
Apple's installers fail to check system hard drive space on initiation and continue to run through the installation process until all storage is exhausted. The resulting failure can lead to an install loop, purgatory in Boot Recovery Assistant with a pop-up reading, "An error occurred preparing the software update," or display of Big Sur's Recovery startup screen that shows no startup disk available.
Macs require at least 35.5GB of free space -- not including the 13GB installer -- to upgrade to Big Sur.
According to the publication, any Mac that is compatible with macOS Big Sur or has downloaded the macOS Big Sur upgrade is vulnerable to the flaw. Testing has confirmed the issue exists in both macOS Big Sur 11.2 and 11.3 beta versions, and is possibly present in macOS Big Sur 11.1.
A failed installation might be the least of a potential upgrader's worries, however, as Macs with a T2 security chip can suffer data loss when FileVault 2 encryption is activated. As detailed by Mr. Macintosh, users are unable to use their Mac's admin password to initiate the recovery process. Further, attempting to reset the password using Personal Recovery Key or AppleID fails, while Target Disk Mode is rendered unusable on Catalina and Big Sur. Passwords do work in TDM on macOS Mojave and High Sierra, the report says.
Data recovery is possible using a system backup and a second Mac, though the process is complicated when FileVault is enabled. Macs that did not have FileVault enabled prior to upgrade can free up space for a new install through a bit of quick file management in Terminal or transferring data to a second Mac via TDM.
Alternatively, users who do not need to recover data from an affected Mac can simply erase the drive and reinstall macOS. Newer Macs with T2 chips require users to go through an "Erase Mac" step, according to the report.
Mr. Macintosh alerted Apple to the issue, and others have complained of identical problems on Apple's Support Forums, but the company has yet to respond.
Comments
This doesn't mean some random form of data lose, it just means you're unable to regain access to the disk, right?
Glad I splurged for a 2TB disk with a 3 their deep backup routine!
1) apple time capsule 3tb
2) SSD 1tb
3) SSD 0.5tb
4) HD 2TB
Backups should really not be a burden for most users, especially if you focus on backing up just your data. Even a pokey sub $100 USB hard disk backup can save your bacon and prevent data loss.
Apple should really upsize the basic memory starting points so there is actually enough room for OS updates and some user data and programs.
Now add to this a significant flaw in the Big Sur installer and you have a setup for people losing data.
It’s been our experience at the office that most ordinary users don’t really keep track of disk space (and some don’t even know how), forcing me to stop buying 256GB Macs, even though we’re nominally working from file servers.
Second NOTHING justifies locking Apple locking access to data owned by people even in security schemes. I noticed that even security is so skewed on Big Sur after upgrading that downloading older Catalina just to make USB stick so it could be used on other computer and you cannot remove that downloaded file from Big Sur unless you go through hoops of disabling SIP (Apple, really? Cannot remove downloaded files to clean up disk in Application space? No wonder that regular user who does not care about crazy steps of SIP may run out of space by mistake just by accumulating some files and apps).
People still prefer local storage rather than iCloud (and cloud in general) because:
1. They are in control of their data - not cloud vendor.
2. They do not want to pay subscription for cloud storage for gigabytes of dormant data they have and daily use maybe 5% of their data (maybe it is time to use something like AWS Glacier for fraction of cost by Apple and others which is deeper storage with different SLAs, but I understand that easy money for cloud vendors is better approach).
3. They do not want anybody manipulate their data for unknown reasons let alone not be sure if it is always secure or could be lost.
4. They learned that data is information about people who became product for analytics running companies - they do not want to be product and prefer making choices without being fed with commercials and ads.
Regardless how big it is, first obligation of any installer software for few decades now on any OS is to check free space on disk and give some buffer for potential other operations (rollback, recovery from installation failure e.t.c.) not to lose users data. Users data take priority over any OS or vendor software. Apparently arrogance of vendors like Apple grew to levels of Microsoft in '90 and post 2000 as I remember. They would learn big lesson if they entered for example financial industry if they lost any data and got sued by big banks over time for outages and recovery during disaster recovery processes.
Example: M1 Mac Mini 512 vs 256GB SSD is $899 vs $699. A 250GB SSD is $55, a 500GB SSD is $80. Suddenly $25 becomes $200???
This issue is gross negligence by Apple and the folks who built and (failed to adequately) test their installer program under customer representative scenarios - including all combinations of memory, storage, video, T1 chip present/not present, etc. Customer data should be treated like currency. Losing customer data is always a very bad thing. The total number of system configuration combinations that Apple has to consider is much more constrained on macOS than on other platforms, like Windows, and is further reduced with the number of older systems that are forcibly deemed and enforced as incompatible. Getting installs and upgrades right should be a relative strength for Apple. They don't fail often, but they failed this time.
Yes, all Apple customers should back up their data, it's common sense. But Apple should not release any application that puts customer data at risk. When I drive my Honda I wear a seatbelt. But my wearing a seatbelt doesn't give Honda the right to ram a truck into my car. Apple created the hazard, regardless of what its users did, including how much storage they purchased when they bought their Apple computer.
I totally agree that Apple overcharges for memory and storage upgrades compared to many other computer vendors. That's a different topic for another discussion. Bringing it up here diminishes the severity and focus of what Apple has done in this particular scenario, i.e., releasing a faulty and highly destructive installer on its customers.
The installer installs into a folder then "shoves" the contents to where it's supposed to be, which is supposed to avoid things like this, though that won't help fiddling with partitions.