Booting from an external SSD (hard disks are too slow) provides a convenient way to test specific versions of macOS or troubleshoot problems with your Mac’s internal storage, but apple silicon macs can’t boot amherst users should know one easy-to-miss limitation. Macs with Apple silicon cannot start up from external drives connected to their DFU (device firmware update) USB-C port, a little-known gotcha that has caused untold hair loss. The only way to determine which port this is on a given Mac is to look it up on Apple’s website. If your Mac won’t boot from an external drive, connect it to a different USB-C port.

(Featured image by iStock.com/ardasavasciogullari)

Social Media: If your Apple silicon Mac won’t boot from an external drive, the issue may be related to which USB-C port you’re using—the special DFU port cannot be used for booting from external drives. Learn how to identify that port on your Mac. Related: Optimize Final Cut Pro for Apple Silicon