macOS Tahoe 26.3 Update Causes External Drive Mounting Issues for Some Users
Following the release of macOS Tahoe 26.3 on February 11, 2026, a subset of Mac users have reported difficulties with external drives failing to mount properly. This issue has been observed across various forums and social media platforms, with users noting that drives which previously functioned without problems are now experiencing mounting failures.
The AppleInsider editorial team has encountered similar challenges, particularly with solid-state drives (SSDs). In some instances, drives used daily have failed to mount, exhibited significantly reduced read and write speeds, or required system reboots to function correctly. More severe cases involve drives that do not mount at all.
For example, a user shared on X (formerly Twitter) that their Samsung T7 SSD, containing critical video files, failed to mount, displaying an error message stating, macOS can’t repair the disk. The message suggested reformatting the drive, which poses a risk of data loss.
While the number of public complaints is relatively low, indicating that the problem may not be widespread, the exact configurations and types of drives affected remain unclear. Notably, the Samsung T7 SSD, which utilizes USB-3.2 Gen 2 connectivity, has been mentioned in user reports.
This is not the first instance of external drive issues in macOS 26. Earlier developer betas of macOS Tahoe had similar problems, which were addressed in subsequent updates. However, the recurrence of these issues in version 26.3 suggests a potential regression or new underlying cause.
Apple appears to be aware of the situation. The release notes for the first macOS Tahoe 26.4 developer beta mention two known issues related to external drives:
1. Some M1 Macs may experience a panic at boot when using an external disk to boot. The suggested workaround is to install to a secondary volume in an APFS container instead of an external disk.
2. HFS external media might fail to mount automatically. Apple recommends using the Terminal tool `diskutil` to mount the disk manually.
These notes indicate that Apple is investigating external drive mounting issues, though the current problem in version 26.3 is not limited to HFS-formatted drives, as APFS-formatted drives are also affected.
At present, there is no definitive solution for users experiencing these issues. The problem does not appear to be widespread enough to prompt immediate action from Apple. Users are encouraged to report their experiences through Apple’s support channels to raise awareness and expedite a resolution.
If you are affected by this issue, please share your specific drive setup, including your Mac model, the type of external drive, and the interface used. This information may help identify patterns and contribute to finding a solution before an official fix is released.
