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Macintosh HD, or the MacBook internal hard drive, is basically the startup drive of most Apple computers. That means if your Mac or MacBook Pro can’t mount its startup disk, it is likely that you will experience problems, like your computer gets stuck on the login screen or it does not boot at all. Situations like this can be very annoying, especially if you have critical and important files stored on the “unmountable” hard drive.

Factory installation disc for 15-inch MacBook Pro. Mac OS version 10.6.7 Disc version 1.0 2Z691-6812-A. Addeddate 2017-08-18 09:32:20. ISO IMAGE download. Apple Startup 9.2.1 repairs problems that may occur when Mac OS 9.1 and Mac OS X are on the same partition and a version earlier than Startup 9.2 has been used. The Utilities folder on the Mac OS X CD contains Startup Disk version 9.2, the control panel you use to select the startup disk for your computer. Here’s how you can add and remove startup items on your MacBook Pro: Add a Startup Item Get to the Users & Groups window Click the Apple logo from the top-left corner, go to System Preferences, and click Users & Groups. This opens the Users & Groups window. From here you can add or remove new users or groups, change password for the users. Testing conducted by Apple in October 2020 on production 1.4GHz quad-core Intel Core i5-based 13-inch MacBook Pro systems with 8GB RAM, 256GB SSD, and prerelease macOS Big Sur. Systems tested with WPA2 Wi-Fi network connection while running on battery power, with display brightness set to 12 clicks from bottom or 75%.

Fret not, because we will teach you what to do if your MacBook Pro won’t mount its startup disk. But before we do that, you better have a backup of all your data.

Backup, Backup, Backup!

Before you proceed with fixing the problem, it is best that you back up all your data first. That way, you can easily retrieve or recover your important documents and files in case something goes wrong.

Now, you might be wondering if it is possible to create a backup of your data, especially that your Mac is not even booting. Here’s what you should know: your Mac has a built-in Disk Utility, which can be accessed before startup. To use this, follow the steps below:

1. Get an external hard drive and connect it to your Mac.
2. Switch off your Mac. After five seconds, switch it back on.
3. After hearing the startup sound, press the CMD and R keys. Hold them until the Apple logo appears.
4. The macOS Utilities window will now appear.
5. Choose Disk Utility and hit Continue to proceed.
6. You can now start backing up your data using the external drive. Once you have backed up all your data, you can try a few fixes to your “unmountable” hard drive problems.

4 Fixes to a MacBook Pro That Can’t Mount Its Startup Disk

In most cases, mounting is an automatic process that happens as soon as the hard drive is connected to a Mac or MacBook Pro. Then again, drive mounting can be performed manually using the Disk Utility of your machine. It will be discussed further below.

Going forward, assuming you already have a backup of your important files and data, let’s proceed with resolving the problem. Below are a few ways to fix a MacBook Pro that can’t mount its startup disk:

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1. Fix Your Hard Drive.

Sometimes, restarting your Mac is more than enough to fix the problem. However, if that does not work, then you might want to look into the angle that there might be something wrong with your hard drive. If that is the case, you have to boot your MacBook Pro in Recovery Mode via Disk Utility.

To hopefully fix your hard drive, follow these steps:

Macbook No Startup Disk

1. Switch off your MacBook Pro.
2. Turn it back on by pressing the Power button. But while doing that, press the CMD and R keys as well until the Apple logo appears.
3. The macOS Utilities window will open. From there, select Disk Utility.
4. From the left pane, choose your MacBook Pro hard drive.
5. Navigate to the First Aid tab.
6. Click the First Aid button to start fixing your drive.
7. Wait for the process to finish before restarting your machine.

2. Run Your MacBook Pro in Safe Mode.

When booted in Safe Mode, your MacBook Pro will start only with the minimum requirements and utilities needed. All other programs and apps that are unnecessary will never be loaded. Hence, if the reason why your startup disk cannot be mounted is a faulty app or program, booting your MacBook Pro in Safe Mode might just fix your problem.

To run your MacBook Pro in Safe Mode, do these:

1. Restart your MacBook Pro.
2. After you hear the startup sound, press the SHIFT key immediately. Continue holding it until the Apple logo appears.
3. If your MacBook Pro boots up properly, then uninstall any program or app you suspect is causing the problem.
4. Restart your machine.

3. Disconnect All External Peripherals.

It is possible that a faulty peripheral connected to your MacBook Pro could be causing your startup disk problems. To verify this, follow the steps below:

1. Switch off your machine.
2. Disconnect all external peripherals connected to your MacBook Pro, including printers, external hard drives, USBs, and scanner. You may leave the keyboard and mouse attached in the meantime.
3. Switch on your Mac. If it boots properly, then one of the peripherals is causing the problem.
4. Identify the exact cause of the problem by connecting each of the peripherals one by one. Make sure you reboot your MacBook Pro every time you connect a peripheral.

4. Reset the SMC and PRAM.

This may sound like a technical solution, but it isn’t. In fact, resetting the SMC and the PRAM takes only a few seconds.

To reset the PRAM and SMC, follow these instructions:

1. Reboot your MacBook Pro.
2. After you hear the startup sound, press the Option, CMD, P, and R keys. Hold them until you hear the second startup tone.
3. Release the keys. Your PRAM will then be reset.
4. Restart your MacBook Pro and check if the problem persists.
5. If resetting the PRAM does not fix the problem, try resetting the SMC. Start by shutting down your MacBook Pro.
6. Plug your machine into a wall outlet.
7. Next, press the CTRL, SHIFT, Option, and Power keys for 10 seconds and release them together.
8. Restart your MacBook Pro and see if it worked.

How to Mount a Startup Disk on MacBook Pro

At this point, you probably want to know how to properly mount a startup disk on your MacBook Pro to avoid problems in the future. Well, mounting a startup disk does not literally suggest physically setting it up with all the wires. It simply means making the startup disk available for your system to perform different read and write operations.

If the startup drive is in good shape, your system Disk Utility should see it. Under the Disk Utility window, select your preferred startup disk. Click on it to mount. By now, your new startup disk should be accessible by your operating system.

What’s Next?

Now that you know how to deal with your “unmountable” startup disk problem, it’s time that you get your MacBook Pro running fast and smooth by downloading and installing a reliable tool like Outbyte MacRepair. Not only will this tool allow you to conveniently find and fix speed and stability problems, it will also protect your privacy. What more can you ask for from such a powerful tool?

If you know other ways to fix a MacBook Pro that can’t mount its startup disk, please share them with us below. We’re looking forward to hearing from you.

To get the latest features and maintain the security, stability, compatibility and performance of your Mac, it's important to keep your software up to date. Apple recommends that you always use the latest macOS that is compatible with your Mac.

Find out how to upgrade to macOS Big Sur, the latest version of macOS.

Check compatibility

If a macOS installer can't be used on your Mac, the installer will let you know. For example, it may state that your Mac doesn't have enough free storage space for the installation or that the installer is too old to be opened on this version of macOS.

Apple Macbook Pro Software Updates

If you want to check compatibility before downloading the installer, find out more about the minimum requirements for macOS Catalina, Mojave, High Sierra, Sierra, El Capitan or Yosemite. You can also check compatible operating systems on the product ID page for MacBook Pro, MacBook Air, MacBook, iMac, Mac mini or Mac Pro.

Create Macbook Pro Startup Disk

Make a backup

Before installing, it’s a good idea to back up your Mac. Time Machine makes it simple, and other backup methods are also available. Find out how to back up your Mac.

Download macOS

It takes time to download and install macOS, so make sure you're plugged into AC power and have a reliable Internet connection.

These installers from the App Store will open automatically after you've downloaded them:

• macOS Catalina 10.15 can upgrade Mojave, High Sierra, Sierra, El Capitan, Yosemite or Mavericks
• macOS Mojave 10.14 can upgrade High Sierra, Sierra, El Capitan, Yosemite, Mavericks or Mountain Lion
• macOS High Sierra 10.13 can upgrade Sierra, El Capitan, Yosemite, Mavericks, Mountain Lion or Lion

Your web browser will download the following older installers as a disk image called InstallOS.dmg or InstallMacOSX.dmg. Open the disk image, then open the .pkg installer inside the disk image. It will install an app named Install [Version Name]. Open that app from your Applications folder to start installing the operating system.

• macOS Sierra 10.12 can upgrade El Capitan, Yosemite, Mavericks, Mountain Lion or Lion
• OS X El Capitan 10.11 can upgrade Yosemite, Mavericks, Mountain Lion, Lion or Snow Leopard
• OS X Yosemite 10.10can upgrade Mavericks, Mountain Lion, Lion or Snow Leopard

Install macOS

Follow the onscreen instructions in the installer. It may be easiest to start the installation in the evening so that it can be completed overnight, if needed.

If the installer asks for permission to install a helper tool, enter the administrator name and password that you use to log in to your Mac, then click Add Helper.

Please allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart, show a progress bar or show a blank screen several times as it installs both macOS and related updates to your Mac firmware.

Learn more

You may also be able to use macOS Recovery to reinstall the macOS you're using now, upgrade to the latest compatible macOS, or install the macOS that came with your Mac.