If you power on your Mac and instead of the usual Apple logo you see a folder with a flashing question mark, your Mac is telling you it can’t find a startup disk to boot from. It’s the Apple equivalent of “No Boot Device Found” on a PC — different operating system, very similar underlying causes.

What’s actually happening

At startup, macOS looks for a valid System folder on a connected drive. If it doesn’t find one — either because the drive has failed, the system has been deleted, or the boot setting has been changed to point at a drive that no longer exists — it shows the question-mark folder.

What commonly causes it

• A failed macOS update that left the system folder incomplete
• A drive that’s failing or has lost connection
• A startup disk preference pointing at a removed external drive
• Filesystem corruption
• On older Macs, an actual hardware failure (the SSD on some MacBook Pros from 2012–2015 in particular)

Step one: pick a startup disk manually

Restart and immediately hold down the Option key (Intel Macs) or the power button (Apple Silicon Macs). On Intel Macs you’ll see Startup Manager — a list of every bootable drive your Mac can see. On Apple Silicon, you’ll get to the recovery options screen.

If your main drive shows up in the list, select it and boot. The Mac may then need to be told this is the regular startup disk via System Settings → General → Startup Disk. Done — problem fixed.

If your main drive doesn’t show up at all, the issue is deeper.

Step two: macOS Recovery

If you can’t pick the drive, boot into macOS Recovery. On Apple Silicon, hold the power button until you see startup options. On Intel, hold Cmd+R during boot.

Once in Recovery, open Disk Utility. Look at the sidebar. If your internal drive shows up but is grayed out or showing errors, run First Aid on it. First Aid fixes a meaningful share of filesystem issues.

If the drive shows up and is healthy but has no macOS installed, you can reinstall macOS from Recovery. This usually preserves your user data, but back up first via Migration Assistant or Time Machine if at all possible.

When the drive isn’t there at all

If Disk Utility doesn’t see the drive even in Recovery, the drive itself has failed or come disconnected. On older MacBooks (especially 2013–2015 Pros and Airs) the internal SSD can fail in a way that makes it invisible. We see this often. Data recovery is sometimes possible through specialized tools, but the drive itself usually needs replacement.

What NOT to do

Don’t reformat the drive in Disk Utility unless you’re sure your data is backed up. “Erase” is permanent. If your photos and documents aren’t backed up to iCloud or Time Machine, walking it in for an attempted recovery is the safer path.

Walk It In

Mac question-mark folder problems are something we work on regularly. Walk it into our 9th Street shop in Durham and we’ll attempt data preservation first. Mon–Fri 10AM–6PM. (919) 314-3327.

Related errors: Mac Prohibitory Symbol, Mac Stuck on Apple Logo.