My mac is missing a serial number

Hi.

If your Mac shows no serial number after a reset, it might be a firmware issue especially if you've already tried wiping and reinstalling macOS.

macOS pulls the serial from the logic board firmware, and if that's missing or corrupted, you’ll see this. That’s also why things like Wi-Fi and iCloud might stop working they rely on the serial.

If it still shows up fine in Recovery but not in macOS, that usually points to the firmware not linking properly during boot. At that point only Apple or an authorized shop can reflash it.

If the Mac had a board swap or came from a third party that could explain it too.

To connect to a Wi-Fi network, you typically do not need the serial number of your device—even if the network uses MAC address whitelisting for security. In such cases, it’s the device’s MAC (Media Access Control) address that matters, not the serial number. The MAC address uniquely identifies the device on a network and is what network administrators use to allow or deny access. Serial numbers are used for inventory or support purposes, but they don’t play a role in the actual Wi-Fi authentication process.