Fix Folder with question mark on Mac

mac question mark folder on a MacBook Air 2020

Updated on 06/08/2023

After years of flawless performance, your Mac has encountered an unexpected issue and is unable to start up today. All you see on the screen is a Mac folder with a question mark. But don’t panic! Before seeking professional help, follow this step-by-step guide to resolve the Mac folder with a question mark problem on your own.

IT-Tech Online is a Mac repair specialist in Australia. It’s our pleasure to share with you the 12 practical tips and tactics to fix the Mac folder with question mark issue.

Many factors could cause the Mac question mark folder issue. All these factors can be categorized into software-related and hardware-related. Depending on what causes the Mac question mark folder issue, the corresponding solution varies from easy to hard. Usually, software-related issues are easy to fix. The hardware-related issues require some equipment and(or) spare parts.

In this guide, we will discuss all the factors and provide comprehensive solutions to solve the folder with question mark mac not startup problems.

If your Mac still displays a flashing folder with question mark, you may need professional help to get your Mac back to work. We will discuss your repair options, the services available on the market and how to choose the best. Good luck!

1. Reset default startup disk

If your Mac displays a flashing question mark for a few moments but then continues to boot, there is nothing wrong with your Mac. You only need to reselect your startup disk in System Preferences. The default boot device of your Mac is NOT set to your bootable hard drive. Your Mac has to search for ALL bootable drives before getting to your current hard disk drive. This search task causes the time delay and you get the momentary flashing folder with question mark. Fixing this problem is very easy.

mac question mark folder - reset disk

1. Choose System Preferences from the Apple Menu and select Startup Disk.

2. Click the lock icon at the bottom and provide your password to unlock the windows.

3. Click the icon of the disk you want to use to start up your Mac. It’s usually named Macintosh HD.

4. Then click the Restart button.

Your Mac should now restart and boot up without the flashing folder with question mark.

Alternately, you can do the NVRAM reset or PRAM reset and your Mac will automatically pick up the right startup disk. 

2. Repair startup disk

If your Mac stays on the flashing folder with question mark all the time, it indicates your Mac is in trouble. But don’t worry, if it is caused by a software issue, you have a good chance to fix it by yourself. Follow these steps to identify whether it is a software issue.

1. Turn off your Mac by pressing and holding the power button for at least 5 seconds.

2. Press the power button once to turn your Mac back on. Immediately press and hold the Command and Option and R keys on your MacBook keyboard to start your Mac from macOS Recovery. Keep these three keys held down until you see the Wi-Fi network screen. 

3. Select a Wi-Fi network and key in the password to connect to the Internet. A copy of the macOS Disk Utilities will be automatically downloaded from Apple’s server to your Mac.

4. Upon finish download, your Mac will run the macOS Utilities and the macOS Utilities screen appears. 

5. Open the Disk Utility from the macOS Utilities windows, if your disk is shown under the internal section on the top left-hand side, your Mac most likely has a software-related issue. If you don’t have any disk listing under the internal section, your Mac definitely has a hardware-related issue. This means your Mac cannot communicate with the hard disk drive at all. Jump to the hardware section below if you have a hardware issue.

6. In the Disk Utility window, select your startup disk and click the First Aid tab.

mac question mark folder -set default startup disk

7. Click the Repair Disk button to verify and repair any issues. If Repair Disk reports issues such as bad sections, you have a hardware issue. This hardware issue is not fatal so you can still see the disk. If the data is important and you don’t have a backup, you may need a professional backup service now. If you are confident in the backup by yourself, go to the data backup section directly.

8. After your disk is successfully repaired, quit Disk Utility.

9. Choose Startup Disk from the Apple menu, select your startup disk and click restart. 

You should be able to boot your Mac if your hard disk only has a mirror software issue. If you still can not boot your Mac, you may need to reinstall the macOS.

Note: If Disk Utility finds issues with your startup disk that it can’t repair, you may need to reformat the hard disk. You should back up any important data on your startup hard disk before erasing it. We discuss the backup procedure in the next section.

3. Reinstall macOS without losing data

If your macOS is not badly damaged, the “repair installation" discuss here may help you to fix the software issues. It requires an internet connection to download macOS from Apple’s server and run the macOS Recovery. If carried out carefully, all your data should be intact. If you already have a bootable external drive containing the macOS, you can speed up the process by running the macOS Recovery directly from your external drive.

 If you don’t have a backup, you need to reinstall the macOS without overwriting the data. The idea is to replace your corrupted system file and fix other software issues without deleting your personal data. Follow the instructions discuss above to download the macOS from Apple’s server through a WIFI connection. 

mac question mark folder - reinstall macOS

Once you are in macOS Recovery windows, choose option 2 “Reinstall macOS", and follow the on-screen instructions. The macOS will be installed into your startup disk without overwriting your data. 

Note: Make sure to NOT use the option 4 “Disk Utility" to erase the disk. It is a good idea to connect the charger to your Mac before starting the installation process. In fact, the recent models of MacBook will insist that you must connect a charger before presenting you an option to proceed with the installation. 

After the installation, your Mac should boot up normally. If your Mac still gets the flashing folder with question mark, you may need to perform a fresh-installation instead of this repair installation. Of course, you need to backup your data first.

4. Backup data and fresh-install macOS 

If the repair installation discussed above cannot fix your problem, you need to fresh-install the macOS. It is always a good idea to do a fresh installation regularly. Fresh installation not only can fix all your software issues but also give you a faster, virus-free and more stable system.

If you don’t have a backup copy of your personal data, time to backup your data now. Use these steps to backup your data to an external drive:

1. Connect an external USB, Thunderbolt, or FireWire drive to your Mac. The drive needs to be the same size or larger than your current startup disk.

2. Use macOS Recovery to erase the external drive, then install macOS onto the external drive. Make sure that you select the external disk as the one you want to erase and install macOS. Take extreme care when you select the drive. Don’t select your built-in startup disk, usually named Macintosh HD.

3. After installation is finished, your Mac automatically restarts from the external drive. When Setup Assistant appears, select the option to migrate your data from another disk. Choose your built-in startup disk as the source to migrate your data from. 

4. When the migration is done, complete the steps of the setup assistant. After the desktop appears, confirm that your data is present on the external drive.

Now you’ve made a backup to your external drive, follow these steps to fix your internal startup disk by performing a fresh installation:

1. Remove your external drive from the Mac. You don’t want to accidentally delete the data you have just backed up.

2. Use macOS Recovery to erase your built-in startup disk and reinstall macOS. This time, you need to select the built-in startup disk as the one you want to erase. When the installation is finished, your Mac automatically restarts from your built-in startup disk. It may take several reboots to complete the installation depending on the macOS version you are installing. 

3. At the end of the installation, the setup assistant appears. You will be presented with an option to migrate your data. Plugin your external drive and wait for a while, your external drive should appear on the desktop.

4. To copy your personal data back to your startup disk, select the option in the setup assistant to migrate your data from an existing Time Machine backup or other disks. Choose the external drive as the source to migrate your data from.

5. Your Mac will restart again on completing the data migration. Verify your data before deleting the data in the external drive. It is a good practice to keep an updated copy of your valuable data regularly. If you have not yet used the Time Machine feature, use it now!

If you’re unable to erase your startup disk or reinstall macOS, your Mac most likely has a hardware issue. Make an appointment with an Apple Genius Bar or an Apple Authorized Service Provider to confirm the issue type. The technicians of these official services are trained well in solving the software issues, but with limited knowledge in hardware. They cannot repair your Mac logic board or SSD drive apart from replacing them. But they are good enough to tell whether your Mac has a software or hardware problem and the service is free. 

If they cannot help due to a hardware logic board issue, try a component-level (chip level) repairer to get your Mac repaired. There are very few component-level repair services available due to the complexity of the mac logic board and Apple’s repair policy. If you cannot find one in your city, you may consider posting your Mac to another city.  Search for a reputable component-level repairer and get a quote before sending out your Mac.

5. Replace faulty HDD cable 

When the HDD cable fails to transmit the electronic signals between the logic board and the hard disk drive, you will get a “mac flashing folder with question mark”. It could be caused by a faulty cable connector on the logic board or faulty HDD cable.

Examine the cable connector and make sure there is no foreign object in the connector. All the pins of the connector should be clean and corrosion-free.

Apple uses flex cable to connect the SATA hard drive to the logic board. The flex HDD cables could be broken due to stress and bent over time.  Failure of HDD cable is very common in the 13” MacBook Pro 2012 model. 

When the flex HDD cable is fitted to the MacBook, it bends to  90 degrees twice on the edge of the super drive shown below. The copper wire inside the flexible plastic tends to be broken at the bent section over time. The defective section can not be seen by naked eyes. It can be detected by a multimeter (continuity test) or examined by a microscope at the bent section. If in doubt replace it with a good HDD cable.

mac question mark folder - faulty HDD cable

mac question mark folder - faulty HDD cable

You can buy a new HDD cable online for only a few dollars. All Apple spare parts come with unique part numbers. The photo below shows the part number of the 15" MacBook Pro 2011 HDD cable. Check your HDD cable and order the spare part by part number so you won’t get the wrong one.

mac question mark folder - Apple HDD cable part number

mac question mark folder - Apple HDD cable part number

6. Fix incompatible firmware

Starting with macOS High Sierra (10.3), Apple upgrades the hard disk drive format from HFS+ to APFS. When you install or upgrade your Mac to High Sierra or later macOS, the installer will automatically upgrade the firmware (low-level system software stored in the ROM chip). If somehow the firmware fails to complete the update, you will get a flashing folder with question mark. This is because the old firmware does not recognise the new APFS format. 

To fix the firmware issue, you need to install High Sierra or later macOS again on your hard drive and your data should be intact. If you really concern your data, you may choose to put in a new SSD hard drive and install the new macOS (10.3 or later).

If all these fail to update the firmware, you can update the firmware manually. This method is also suitable for the IT department in organisations who need to update a lot of Macs’ firmware at the same time and deploy new macOS without going through the installation process individually for every Mac.

1. Put in a new SSD hard drive in a MacBook.

2. Install any macOS older than High Sierra 10.3 e.g. El Capitan or Sierra.

3. Go to AppStore and perform a software update.

4. Choose High Sierra or later macOS and continue the update

5. Your Mac will reboot and start the software update.

6. Stop the update. Your goal is to download the macOS, not to update the macOS. 

7. Now check the Application folder, you should be able to see the downloaded macOS file.

8. Open Terminal Utility and copy the following codes and enter. You will be asked to enter the admin password to complete the task.

     echo “Mounting High Sierra ESD disk image…"

     /usr/bin/hdiutil mount /Applications/Install macOS High Sierra*.app/Contents/SharedSupport/InstallESD.dmg

     echo “Expanding FirmwareUpdate.pkg"

     /usr/sbin/pkgutil –expand /Volumes/InstallESD/Packages/FirmwareUpdate.pkg /tmp/FirmwareUpdate

     echo “Running Firmware Update"

     cd /tmp/FirmwareUpdate/Scripts

     sudo /usr/libexec/efiupdater -p “$PWD/Tools/EFIPayloads"

9. The firmware in your Mac will be updated on the next startup, so reboot your Mac now.

10. Put back your original HDD and you will see the Apple logo. If your task is to update the firmware to many Macs at the same time, remove the SSD hard drive and put it in the next target Mac, repeat the steps 8 and 9.

Note: The above codes will compare the current firmware version of your Mac with the firmware version extracted from the macOS you have just downloaded. If the extracted firmware is newer than the current firmware, a firmware update procedure will be scheduled on the next startup of the Mac. 

mac question mark folder - Firmware update

The above picture shows that the extracted firmware version [007F0000] is newer than the current firmware EFI version [00770033] of your Mac. So the firmware will be updated to the new version on the next startup. Also, it is very important that you need to stop the upgrade process after downloading the newer macOS, as the download file will be automatically erased after finishing the software update. Our codes need to extract the embedded firmware from the file.

Mac question mark folder Firmware update screen recording:

7. Check faulty lifeboat connector

In 13” and 15 MacBook Pro  A1706 and A1707 Manufactured in 2016 2017 with Tochbar, there is a  connector called lifeboat to connect the SSD circuit to the CPU so the CPU can read and write data to the SSD chips by inserting the lifeboat cap. In a disaster situation when the logic board is not functional any more, we can remove the lifeboat cap and connect a device called a data migration tool. Therefore we can retrieve the data from the dead logic board.

mac question mark folder - faulty lifeboat connector

mac question mark folder - faulty lifeboat connector

If somehow the lifeboat connector cap is not functional, you will get the flashing folder with question mark. Remove the lifeboat connector cap and examine it. Make sure there is no corrosion and clean it if necessary. All the pins of the lifeboat connector and the cap should be free of corrosion or dust.

mac question mark folder - lifeboat connector cap removed

mac question mark folder - lifeboat connector cap removed

8. Check faulty SSD socket

All the removable SSD drives are connected to the Mac logic board via the SSD sockets. If the socket is corroded, you may get a “flashing folder with question mark”.

Usually, the corrosion is caused by exposure to liquid or bug droppings. Use a small sharp knife to cut off the corrosion then use 99% alcohol and a toothbrush to clean the pins on the SSD drive and the SSD socket. If the socket is damaged so badly you need to replace the socket. You need to have micro-soldering skills to perform this task or use a professional component-level logic board service.

SSD drive and SSD socket on Mac logic board

SSD drive and SSD socket on Mac logic board

9. Check faulty hard drive

If your hard drive is faulty, the logic board cannot communicate with it, you will get a “mac flashing folder with question mark”. 

All pre-2013 MacBook and MacBook pro use mechanical hard drives. The majority of Apple iMac also use mechanical hard drives. These mechanical hard drives are prone to mechanical failure. If you can hear the clicking noise coming from the hard drive, you definitely have a faulty hard drive.

Another common problem for spinning drives is the motor getting stuck. Put your hand on the drive and switch on your Mac. If you cannot feel the vibration of the hard drive spin motor, the hard drive is faulty. Your Mac cannot find the bootable drive then display the question mark folder.

If the spinning hard drive is faulty, it is the time to upgrade to SSD drive now. MacBook Pro SSD upgrade and iMac SSD upgrade will significantly improve the performance.

If you have an SSD drive, switch on your Mac and wait for five minutes or so. Put your finger on the SSD controller chip ( the biggest chip). If the chip is cool, your SSD is dead. The SSD does not receive any power at all.

The above diagnoses are based on the assumption that your Mac logic board is good. If in doubt, get a known working Mac and try your hard drive again. If you still get a question mark folder, you have a good chance that the hard drive is faulty even though you can feel the motor spinning or SSD controller warming up.

On some 2013 to 2015  Samsung SSD drives, the SSD controller may develop crack soldering ball issues after continuing to expose to high operating temperature. If you put the drive in an oven at 180 to 200 Celsius degrees for two minutes,  it might work again as the cracked balls have been joined again. If the data is very important, do not try this method, get a reputable mac data recovery service provider as soon as possible. Please note that the second attempt to recover the data from a faulty hard drive is much harder or even impossible as the first attempt already destroyed some or all the data.

10. Flash EFI firmware

If something went wrong while you were updating the macOS, you may get the flushing Mac folder question mark. This is because the update program has already made some modification to the system EFI chip but failed to complete the task, therefore you end up with a corrupted EFI firmware.

We need to get access to a working Mac. This Mac must be the same model and same manufacture year with your one. You are going to retrieve the EFI firmware from this working Mac. Alternatively, you can download the firmware from the internet and make sure the logic board part numbers are the same.

Once you have the firmware, you need to modify the ME region (Intel Management Engine code) of the EFI codes and serial number before writing the codes to your in-trouble Mac.  

1. Connect the  EPROM programmer to the programming port of the working Mac.

2. Read the code from the Mac and save it as a file.

3. Use a hex editor to replace the ME region with a fresh compatible ME.

4. Replace the serial number with your own Mac.

5. Write back the modified code to your in-trouble Mac

6. Power up your Mac and perform a PRAM reset.

Now your Mac should be able to boot normally to the macOS and no more flashing question mark folder.

Note: In every Mac, the Intel Management Engine (ME) of the EFI code is “married” to the individual CPU/PCH inside the Mac. This is why you need to replace the old ME with a fresh one. 

11. Remove EFI firmware lock

If your Mac is locked by the EFI password, you may see the flashing Mac folder with question mark. This password is different from the password that you use to set up the macOS account. The EFI password is stored in the EFI chip soldered on the logic board. It will lock the whole logic board. You can not use the option key function to guide the logic board to boot from an external HDD or simply replace the internal hard drive. 

By contrast, the macOS account password is stored in the hard drive. You can get rid of the password by erasing the macOS completely or simply put another hard drive in the Mac. In other words, macOS account password protects the data in the hard drive while the EFI password prevents unauthorised access to the logic board.

There are a lot of reasons why the Mac is locked by EFI password and we are not going to address the reasons in this guide. We emphasize on how to remove the EFI lock.

There are two ways to fix this problem, replacing the whole logic board and clearing the password code stored in the EFI chip. We discuss the latter method here.

1. Remove the EFI chip from the logic board

2. Place the chip to the EPROM programmer

3. Read the EFI code and save as a file

4. Use a hex editor to open the file you just have saved.

5. Search for $ssv and replace the current row and next 12 rows with hex FF. This will clear the EFI lock code. 

6. Write back the modified EFI code to the chip.

7. Solder the chip back to the logic board.

Congratulations!  If you come up to this point, you just pass the intermediate level and enter into the advanced level of fixing Mac folder question mark issues.

The following “Mac folder question mark” case studies are hardware related and require chips replacement known as component-level repair. In order to perform the repair task, you need to have the micro-soldering skill, Apple mac logic board electronic diagram ( schematics) knowledge and some equipment.

12. Repair Mac logic board

MacBook Pros manufactured after 2015 always use SSD onboard technology. The SSD chips are soldered on the logic board in the MacBooks. You can’t remove the SSD drive and plug in a new one, just like the pre-2016 MacBook Pros and the pre-2018 MacBook Airs.

When you have a folder question mark on an SSD onboard MacBook and have already ruled out any software issue, you most likely have faulty SSD circuits on the logic board.

There are two types of faults in SSD circuits. The first one is the SSD NAND chips are ok, but the power rails (DC power in different voltages, e.g., 2.7V, 0.9V, 0.8V, etc.) to the SSD chips failed. You need a Mac component(chip) level repairer to repair the power rails. After repair, your data usually will be intact.

The second type of fault is failed SSD NAND chips. When any SSD NAND chips fail, your data will be gone. There is no way to retrieve the data. You can replace the whole set of SSD NAND chips, the SSD controller chip and the Apple T2 security chip. The repair bill usually is costly. You may find that a replacement logic board is cheaper.

Below we take a MacBook Pro and a MacBook Air to demonstrate how to fix the mac folder question mark at the component level.

MacBook Pro 2017 SSD repair

Equipment used: Hot air gun, soldering iron, Apple logic board schematics.

Computer Model: A1706 13” MacBook Pro 2017 touch bar

When we switch on this MacBook, we get the Mac question mark folder straightaway. Then we connect an external bootable SSD drive to the mac, we can boot into macOS and everything is working fine. Based on this test, we lock-in the fault is in the SSD circuit section. The SSD chips are soldered on the logic board in this MacBook.

Open the back panel of the MacBook and examine the logic board. Remove the lifeboat cap on J9600 and clean the connector as well as the cap. Reinstall the cap and turn on the Mac, we still get the flashing question mark.

MacBook Pro folder with question mark - caused by missing SSD chip power rail.

There are 8 power rails for the SSD circuit in this model. We need to measure them one by one. One of the 1.2V rail PP1V2_SSD_COLD is missing.

U9300 SSD power management chip is responsible for creating the 1.2V power rail. PICCOLO_IUVD is the enable signal to tell U9300 to create 1.2V PP1V2_SSD_COLD.  When we measure PICCOLO_IUVD the voltage is 0V and is not OK. We spotted something one the resistor R9350. Put the logic board under the microscope, we have found a bug dripping on the resistor and corroding it. Replace the resistor and we get the Apple logo instead of the Mac question mark folder.

MacBook Air 2017 mac question mark folder repair

Equipment used: Hot air gun, soldering iron, Apple logic board schematics

Computer Model: A1466 13” MacBook Air 2017

Logic board number: 820-00165

There is a removable SSD drive in this model of MacBook. Remove the old SSD drive and put in our known-working SSD drive, we still get the Mac question mark folder. This is confirmed that the fault is in the logic board, not in the SSD drive.

Measure all the power rails, data bus and reset control signals on the SSD connector. They are all working fine. The fault must be in the SATA control circuit in the CPU side.

MacBook Air folder with question mark – caused by missing PCH 1.05V power rail

There are few power rails to power up the CPU SATA controller. When we measure the PP1V05_S0SW_PCH_VCCSATA3PLL, the voltage is 0.6V. The correct voltage should be 1.05V. This power rail is for SATA clock generator inside the CPU. If this power rail is missing, the CPU cannot get the SATA clock, therefore cannot communicate with the SSD drive.

Further investigation shows that the inductor L1290 is faulty. It cannot fully pass the 1.05V voltage from one end to the other end. Replacing the inductor and the MacBook works fine.


13. Common Questions

What is folder with question mark on Mac?

When you switch on a Mac, instead of displaying the Apple logo, your Mac screen shows a mac flashing folder question mark in the centre. If you have a pre-2015 Apple computer, you may hear the chime before you see the question mark folder on mac. The Mac folder question mark issues could occur across the Apple Mac computer products including MacBook, MacBook Pro, MacBook Air, iMac, Mac Mini and Mac Pro as they are all working on the same operating system – macOS.

Why do I get the flashing folder with question mark?

The mac question mark folder indicates that your Mac cannot locate its system boot folder. Therefore your Mac cannot load the macOS from the hard drive to the memory to start up the macOS. In plain English, the mac question mark folder means:
* Your startup hard disk or logic board is faulty – hardware-related issues or
* The startup disk doesn’t contain a WORKING copy of macOS – software-related issues.
In order to quickly diagnose and fix the mac question mark folder issues for your MacBook, iMac, Mac Mini and Mac Pro, you need to understand how an Apple Mac loads the macOS from the hard drive.
When you turn on the Mac, the CPU will perform a task named “Power On Self Test”. Your Mac will chime after passing the test, then search for a “loader" from the available bootable-devices such as hard drives, optical drives or USB drives. If no bootable-drive is found, or the bootable-drive found does not have a working loader, your Mac will display a flashing folder with question mark. If a valid loader is found, your Mac will display the Apple logo. The CPU then executes the codes of the loader and loads the rest of Apple’s macOS software into your Mac.

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