Bluetooth won't turn on, or the switch is greyed out
Quick answer
Open Bluetooth in System Settings and try the switch once more, then restart your Mac. If the switch is still greyed out after a restart, run Apple Diagnostics to check the hardware.
Why it happens
Bluetooth on a Mac is run by a small background service. If that service gets stuck, often after an update or a long sleep, the switch stops working or turns grey. A restart reloads it. If Bluetooth still won't load, the Mac may not be detecting its Bluetooth hardware at all.
How to fix it
If you use a Bluetooth mouse or keyboard, plug in a wired one or use your MacBook's trackpad for now, so you can still click around.
Open the Apple menu, choose System Settings and click Bluetooth in the sidebar. Click the Bluetooth switch at the top once, then wait a few seconds to see if it stays on.
Bluetooth
If it won't switch on, restart your Mac from the Apple menu. Restart, not just sleep, so the Bluetooth service starts fresh.
Apple menu›Restart…
After the restart, open Bluetooth again and turn the switch on. You can also try it from Control Center, the two-switch icon in the menu bar.
Still not fixed?
Unplug every USB device, hub and dock, then restart again. A faulty accessory can stop Bluetooth loading.
Install any waiting update. Open General, then Software Update, and let it check. Bluetooth bugs are often fixed in point releases.
General›Software Update
Shut down completely, wait 30 seconds, and start up again. This gives the Bluetooth hardware a full power cycle that a restart doesn't.
Run Apple Diagnostics. Unplug accessories and shut down. On a Mac with Apple silicon, press and hold the power button until the startup options appear, then press Command-D. On an Intel Mac, press the power button and hold D right away.
If Diagnostics reports a fault, or the switch is still greyed out or Bluetooth is missing from System Settings, it's most likely a hardware problem. Contact Apple Support or book a repair with an Apple Authorized Service Provider.
Terminal
Open Terminal (Applications › Utilities), paste this line and press Return.
sudo pkill bluetoothdNothing to undo: macOS restarts bluetoothd automatically.
This one needs your Mac's admin password. Copy it and run it yourself in Terminal, and only if you're comfortable doing that.
Pro details
Restarts the Bluetooth daemon without rebooting.
Questions people ask
Why is my Bluetooth greyed out on my Mac?
The Bluetooth service is usually stuck. Restart the Mac with accessories unplugged. If it stays grey, run Apple Diagnostics, as the hardware may not be detected.
Can I use my Mac without Bluetooth while I fix this?
Yes. Use the built-in trackpad and keyboard, or plug in a wired mouse and keyboard. Wi-Fi works on its own, so you stay online.
Does resetting the Mac fix Bluetooth?
You rarely need to go that far. A restart, unplugging accessories and installing updates fix most cases. If those don't help, Apple Diagnostics tells you whether it's hardware.
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