(Un)Marked Mac OS

Posted on 5/7/2021 by admin

With no warning in advance, a flashing folder with a question mark appears when your Mac startup.

(unmarked Mac Os X
(unmarked Mac Os Catalina

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What does it mean? A folder with a question mark icon means that your startup disk is not detected or doesn't have a usable Mac operating system.

Commonly, the folder with a question mark happens after you've booted from an external system drive recently, replaced a new HD or SSD, or updated a recent macOS. It could see that both software and hardware errors are the possible causes.

For the worst situation, you can't go past the question folder icon, even with a restart. So, to avoid data loss, recover files from your Mac first. Then, follow the solutions below to get rid of the blinking folder with question mark and boot up your Mac as usual.

Here are the solutions to fix the folder with question mark on Mac in this post:

The name 'Mac OS' was, allegedly, created when Apple started its program to encourage Macintosh clones; the intent may have been to provide branding for the OS, separate from the hardware. 'Mac OS X' was probably picked as a name to suggest continuity with the earlier OSes with 'Mac OS' in their names, even though Mac OS X was a new OS. From the Apple menu in the corner of your screen, choose About This Mac. You should see the macOS name, such as macOS Big Sur, followed by its version number. If you need to know the build number as well, click the version number to see it.

1. Check Startup Disk preferences
2. Reselect the startup disk in macOS Recovery mode
3. Repair the startup drive with Disk Utility
4. Reformat the startup drive and reinstall macOS
5. Check and replace the startup HDD cable
6. Update firmware of your MacBook
7. Check the lifeboat connector on the logic board
8. Check the faulty SSD socket or hard drive on Mac logic board

Recover data from Mac showing a folder with a question mark

You can watch this video to learn how to recover data from Mac that won't boot due to the folder with a question mark.

Data recovery is the first thing once your Mac won't boot, which can prevent forever data loss caused by some fixes. As the Mac is unbootable, you can only recover data with data recovery software like iBoysoft Mac data recovery.

Go to run iBoysoft Mac data recovery in macOS Recovery mode to get the lost files back. If you don't want to check the details, watch the above video instead.

How to fix the folder with question mark on Mac

You could see the folder with question mark on MacBook Pro, MacBook Air, iMac, or Mac mini. But anyway, you can try to reset NVRAM on your Mac first. If it doesn't work, try the following solutiuons one by one.

1. Check Startup Disk preferences

If your Mac displays a flashing folder at startup, you can wait for a moment and see if it can boot past the icon.

If fortunately, it continues booting up, congratulations! But just in case, you can reselect a startup disk in Apple menu > System Preferences > Startup disk.

If you Mac can't boot past the flashing question mark, you can manually select the startup drive. You can do this by restarting your Mac while holding down the Option key.

If you boot from an external drive, you can check these factors.

Make sure the hard drive is powered on, especially for some desktop drive that needs an external power source.
Make sure the USB port and cable is working.

Tips: In the case of some older Mac OS X machines, you can boot from the install DVD or CD that comes along with your Mac in the optical drive.

2. Reselect the startup disk in macOS Recovery mode

When the first method won't work, you can boot into macOS Recovery mode. The built-in recovery system of your Mac allows you to reselect the boot volume to fix the flashing folder with a question mark on Mac without CD.

To do this, you can follow these steps.

1. Force your Mac to shut down by pressing the power button for seconds.
2. Identify if you are using an Apple Silicon M1 Mac or not, restart your Mac and immediately press one of these key combinations to boot into macOS Recovery mode.
Note that the way to boot into macOS Recovery Mode on M1 Mac is different from old Macs.
3. When you see the Apple logo or it's loading recovery options, you can let the keys go.
Once you see the four macOS Utilities as below or similar, it means you have booted into macOS Recovery mode.
4. Then, you can click on the Apple logo at the upper left, choose the Startup Disk option.
5. Reselect the correct Mac startup hard drive that holds a macOS.

After you click on the Restart button, your Mac should then start up without the blinking folder with question mark.

Tips: If you can't boot into macOS Recovery Mode from the local recovery system, try Internet Recovery mode by replacing the keys in Step 2 with Option + Command + R (or Shift+ Option + Command + R). Make sure your Mac connected to the Internet at the same time.

3. Use Disk Utility to repair the startup disk

If you can't see any startup option in the Startup Disk window, probably, the startup drive is corrupted and that is the cause for the folder with a question mark on your Mac.

Then, you need to check and repair the hard drive with First Aid to boot your Mac from this drive.

The worst situation is that you don't see your built-in startup disk even in the Disk Utility. It indicates that there's a hardware issue. You need to check the connections of your hard drive or contact the Apple authorized service for Mac repair.

Some other times, the startup drive is showing up in Disk Utility. However, Disk Utility finds issues with your startup disk that it can't repair. In this case, you need to move forward to the next part.

4. Reformat the startup drive and reinstall macOS

After trying First Aid, you still see a folder with question mark during Mac rebooting, which means your startup disk has serious corruption. You need to reformat it and assign a new file system.

However, reformatting will wipe your files off the hard drive. If you don't have a backup of your Mac, you would lose important files after reformatting.

However, you can follow this safe guide to reformat the startup disk without data loss:

1. Recover data from Mac that won't turn on. (Of course, you can ignore this step if you have a backup.)
1. Boot your Mac into macOS Recovery Mode and select Disk Utility from the macOS Utilities.
2. Select the startup drive in Disk Utility and click on the Erase button at the top menu.
3. Name it as Macintosh HD, choose GUID scheme, and APFS format if you want to use macOS 10.13 and later.

Now, you'll have a fresh new Mac hard drive but it contains no Mac operating system. To boot your Mac up without the flashing folder with question mark, continue with reinstalling macOS in macOS Recovery mode.

How to Reinstall macOS to start up the Mac?

Here is a guide to reinstall macOS to start up your MacMacBook Pro, Mac mini, MacBook Air, and iMac. Read more >>

5. Check and replace the startup HDD SATA connections

You internal Mac hard dirve is working on the basis of HDD cable transmitting the electronic signals between the logic board and the hard disk drive. Therefore, once it's loose, damaged, broken, or deformed, you might get the Mac folder with quesiton mark at startup.

Here is how can you check the connector of the startup HDD. Note that ask someone prefessional to help you do this job is necessary.

Check and remove any foreign object on the connector
Make sure the connector is clean and corrosion-free
Check if the flex HDD cables are broken or damaged due to overstress and bent.

The SATA hard drive is connected to the logic board in your Mac in the way of bending 90 degrees twice. This particularly can be seen in 13' MacBook Pro 2012 model (on the edge of the super drive).

So, it's likely that the copper wire inside the flexible plastic cable is broken or damaged at the bent section.

Then you'll need to replace it with a good HDD cable.

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If your Mac mini, MacBook Air, or MacBook Air shows folder with a question mark, you can check the SATA connection like this.

1. Open up the cover of the Mac.
2. Find the SATA connection of your hard drive. You can remove the connection and then clipped it back firmly.

This works well if your Mac doesn't recognize the internal hard drive for booting up. But if it doesn't help, either the hard drive or the SATA connection is damaged. You'll ask for a repair or replacement service from Apple.

6. Update firmware of your Mac Computer

If you see the Mac folder with flashing question mark after a recent macOS update, it may be a result of incompatible firmware that should be automatically upgraded by the installer.

Possibly, the firmware fails to complete the update during the whole system update. Then, the new system can't be recognized by the old firmware, causing boot issues.

To re-update the firmware, you can manually erase the disk and reinstall the macOS with stable network connection and enough free disk space.

7. Check the lifeboat connector on the logic board

Inside MacBook Pro in 2016 and 2017 with Tochbar, a critical bridge connector called lifeboat is used to connect the SSD circuit to the CPU so the CPU can read and write data to the SSD chips.

However, if you have send it for repair and forget to put it on, or if the lifeboat connector cap is not functional, you will get the flashing folder when turning on Mac.

Here are some basic checks you can perform to make it work again (Do these checks with someone professional):

Make sure there is a lifeboat cap and it's on.
Remove the lifeboat connector cap and check if it's corroded or dusty.

8. Check the faulty SSD socket or hard drive on Mac logic board

Sometimes, Mac can't find the startup drive just because the drive itself is in trouble.

Your removable SSD drives on the Mac logical board is connected using SSD sockets. Once these components are corroded, damaged, or dusty, you'll receive the 'Mac folder with question mark' error on Mac booting up.

So, think if you have spilt any liquid on your Macbook Air or Pro. If you see the SSD socket is corroded, you can cut off the corrosion and map the pins with 99% alcohol. If it doesn't help, you need to replace the socket.

For most Apple iMac, pre-2013 MacBook and MacBook pro that use mechanical hard drives, the Mac flashing folder with question mark appear when there is a mechanical disk failure, and you might hear beeping or clicking noise. Or if you can't feel the vibration of the hard drive spin motor, the hard drive is dead.

Go ahead to replace or upgrade it with SSD, and reinstall Mac operating system.

Conclusion

Most of the time, errors like the circle with line through it and the folder with a question mark on the Mac/MacBook screen means a system software issue. You can simply fix this by reinstalling macOS (Remember to recover data first).

If macOS reinstallation can't fix the Mac flashing folder issue, it could also result from the hardware issues. In this case, you'd better send your Mac to a trusted repair store.

Update 1

Symbols for this stack below (thanks Rasmus!)

Update 2

Based on the hackernews comments, some people have hit this and others haven't, and using external displays is a factor. Some have said that they have had issues with 10.9.2 as well, or all the 10.9 series. Perhaps it is a problem with a particular graphics card driver (myself and my coworkers have the retina Macbook Pros), but that's just a guess. The decoded stack above includes HFS calls, but that makes no sense, unless the graphics driver was stepping on random memory (which are among the worst panics to debug).

EDIT: After learning that this doesn't affect everyone, I changed the title of this post from 'Is Toxic' to 'Recurring Panics'. I also removed the words 'infected' and 'disease', which were off-putting.

Update 3

I got another new macbook pro, running 10.9.2 (although, a different kernel version), and switched using migration assistant. It worked great, initially. Then I had five panics in a row when connecting to different remote displays. In case migration assistant moved over some corrupted preferences, I got another new macbook pro, with 10.9.2, and just began using it fresh, and was still able to reproduce the panics (running only Firefox and Chrome, this time). I don't know if these panics are the same as what I had on 10.9.3, since I only have hex dumps to compare. 10.9.3 seemed to panic much more easily.

I'm a little fed up of the typical macbook debugging technique: switch things until the problem goes away. I'm also fed up with seeing stack traces that are inscruitable hex. I want to read the stack traces, and understand what the kernel is doing that led to the panic. So I studied how Rasmus had translated my earlier stack, and I learned that the default kernel (mach_kernel) does have some symbols, which aren't used in the diagnostic reports. Excellent. I can write a quick helper tool for translating stacks.

Update 4

I wrote kernel_diagreport2text.ksh, a tool that translates symbols from OS X kernel diagnostic reports using two different techniques. It is here on github.

Here's my new 10.9.2 macbook panics, summarized by kernel_diagreport2text.ksh:

I wish I had this tool earlier! It uses atos(1) for symbol translation, and decorates remaining addresses with kernel extension names (eg, 'in com.apple.driver.AppleUSBHub') if available in the diag report. It does not need the Kernel Debug Kit installed, although if it is, you should get more symbols translated.

That output is for a default 10.9.2 system, and while many symbols are missing, we can still learn a lot. All of these panics are in VM, and don't look the same as the 10.9.3 panic that was translated earlier.

To run this yourself, download (or save) the raw script. Then open up Terminal (which is under Applications->Utilities) for a command line, and you can run it on your saved kernel diagnostic reports. The steps are likely something like this (depends where your browser has downloaded the file):

This script is (obviously) not an official Apple diagnostic tool, and is provided as-is with no warranties or guarantees. It does not need to be run as root.

Update 5

29-May-2014. I've partially translated my 10.9.3 panics, using my kernel_diagreport2text.ksh tool described earlier. Here are some key examples:

The others showed similar stacks. These are also all in VM, either page faults or an explicit panic() call in the VM_PAGE_QUEUES_REMOVE macro.

To translate my 10.9.3 diag reports with the kernel_diagreport2text.ksh script, I needed a copy of the 10.9.3 mach_kernel (I'm back on 10.9.2), and to edit the script to point to it (update: that's now the -f option). Apple's auto update had already downloaded the 10.9.3 update, putting it in /Library/Updates/031-02348/OSXUpd10.9.3.pkg. That pkg file turned out to be Russian dolls: a xar, containing a bzip2 file, containing a cpio archive, which contained the 10.9.3 mach_kernel.

If you ever want to do something similar yourself, you really want to make sure the mach_kernel matches what you have in the diag report, otherwise the translations will be incorrect. Eg:

Those match! The source for xnu-2422.100.13 isn't out yet, but when it is, it should be under opensource.apple.com/source/xnu. I've been browsing the earlier version to get a handle on the VM code.

Update 6

After a quick browse of the VM code, it looks like a double free, based on the VM_PAGE_QUEUES_REMOVE panic. It's possible the other VM panics are manifestations of the same bug. These are nasty bugs to debug, as the engineer must track down the earlier free. This is harder than it sounds, as free's occur so frequently. I could run out of memory trying to log them for later lookup.

But after using DTrace on the vm_page_free_prepare_queues path, I'm not sure it's a double free using the vm_* interface, as mem->free was not set. Which suggests something even nastier – someone else is stepping on memory, perhaps zero'ing it out. Now if two paths are fighting over the same memory, and if I'm lucky, they do so in either order with the 2nd hitting the panic. Which could mean I've already captured both paths in the earlier panics. The IOBufferMemoryDescriptor::free() could be the non-VM path that's freeing memory, coming from IOAcceleratorFamily2.

This is just speculation - I don't know what the real cause is yet. But given the nature of the panics (external displays), the partially-translated stacks, the open source xnu kernel, and DTrace to test theories, I have a lot of clues. The hardest part is finding time to put into this.

Update 7

(unmarked Mac Os Catalina

Here's an older panic excerpt (OS X 10.5.8):

Notice something? This has arguments for the stack functions, which are incredibly useful when doing panic analysis, especially when all we have to go on is the panic report file. So where did these args go in 10.9?

From the xnu-2422.90.20 source, osfmk/i386/AT386/model_dep.c:

PRINT_ARGS_FROM_STACK_FRAME needs to be set. It's set in the same file:

(shakes fist.) No comment, no explanation, just zero that guy. Why?

I think the reason can be explained by an earlier kernel version, xnu-2050.9.2:

Ah. Stack frame arguments are architecture specific, and the code was written for i386, but not x86.

It should be a fairly easy enhancement for Apple to add the x86 code, and greately enhance all kernel panic reports.

Update 8

30-May-2014. I have a workaround in hand for Mavericks 10.9.2: turn off Firefox hardware acceleration. With this off, my panics have now stopped. Perhaps this works on 10.9.3 as well, if it is the same panic. The setting is under Preferences->Advanced->General.

Other applications use hardware acceleration as well, so you may need to disable it elsewhere, if you believe you have this bug. For me, the easiest way to duplicate the panic was to run a youtube video full screen in Firefox, then plug in a remote display, and close the laptop lid. A few cycles of that usually led to the same type of panic I was hitting earlier. And with hardware acceleration disabled, it worked fine.

I still feel this was much worse in 10.9.3 (if I had more time, I'd confirm). The 10.9.3 update did say that it 'Improves 4K display support', which may have modified the hardware acceleration routines.

I suspect hardware acceleration was freeing or stepping on memory it shouldn't, which led to the VM panics. I'd like to write more about this, including where I was in the analysis, and ideally identify the root cause, but now that I have a workaround it's no longer a priority to work on. I may do a follow up blog post later when I have the time. I wanted to share the workaround ASAP.

This information has been filed as Apple bug ID 17082120. (This is in addition to the 30 or so Kernel diag reports I've sent their way.)