MacBook Pro M4 Pro (24GB/512GB) stuck in boot loop — kernel panic “ANS2 Recoverable Panic / apcie0[2] Unexpected link down”

You are correct that the Kernel Panic is associated with an SSD. If you have an external Thunderbolt 3/4 SSD, then it is possible the Kernel Panic could be referring to the external SSD. I saw one post where the user confirmed it was an external SSD causing the issue. An external NVMe SSD connected through Thunderbolt is connected to the PCIe bus since a Thunderbolt NVMe SSD does show up as an NVMe SSD. Not sure about USB4 or 3.

Otherwise, the internal SSD is most likely failing. "Unexpected link down" indicates the SSD is not connected which is one of the most common symptoms associated with a failing SSD in my experience....usually the SSD is unable to go ready when first powering on such as when powering on the computer or waking the computer from sleep.

I would suggest disconnecting all external devices to make sure they are not the cause.

I would not think Windows in a VM would cause the problem, but you can disable the VM to see if that makes any difference.

Otherwise, your only option would be to try a DFU Firmware Restore which resets the security enclave chip, system firmware, and internal SSD and pushes a clean copy of macOS to the internal SSD. I really don't think this procedure will help, but it is about all you can do without resorting to an Apple repair involving the replacement of the Logic Board.

cenzowm wrote:

I'm only afraid of what apple technician can understand about the problem.

Yeah, most techs and first tier Apple support have no idea how to interpret Kernel Panics.

I red a lot post where the problems was "solved" only formatting and then all was like before (so not fixed).

That goes for almost all issues since a clean install is always Apple go to....it is justified though if troubleshooting configuration issues and third party software is unsuccessful. It is the quickest way to confirm a hardware or software issue as well as long as thorough testing can be done before installing any third party software, or restoring/migrating from a backup.

See if putting the laptop to sleep for 15 minutes, then waking it up is able to trigger the Kernel Panic more often. You may need to extend that sleep period for longer as that is just a quick example. If you can reproduce the issue on demand for the Apple tech, it will really help in this case.

Have you noticed any patterns when the Kernel Panics occur which may give you a clue to how possibly to reproduce the issue more often?

You can also try showing the tech copies of the Kernel Panic logs pointing out the critical parts of the Kernel Panic. The following may help you to help the tech understand it if the tech is willing to listen & think a bit about it:

ANS2 == Apple NAND Storage 2 which means the SSD

apcie0[2]: Unexpected link down == PCIe bus where it lost a link to the aforementioned SSD (ANS2)

FYI, there are multiple posts on this forum over the last few years where people have reported various types of these ANS2 Kernel Panics (there are a few different variations of them) and a few people did update their threads to confirm Apple had to replace the Logic Board to solve the problem.

Please keep us updated with how things go.

Good luck.

zongzi778 wrote:

I also encountered this problem. I activated it on October 18th, so it's been activated for about 25 days. Four days ago, it suddenly crashed and restarted. After restarting, I checked the problem report and got the following:

panic(cpu 0 caller 0xfffffe00398e6250): ANS2 Recoverable Panic - assert failed: [14510]:apcie0[0]: Unexpected link down linksts=0x83000204 pcielint=0xf0017000, ltssm=0x00(DETECT_QUIET) - power(14)

If you get this Kernel Panic with all external devices disconnected, then it seems your internal SSD is failing.

The Kernel Panic you quoted clearly states the SSD experienced an unexpected disconnect. You may have overlooked my post earlier in this thread due to the chaotic ordering produced by the forum's "Ranked" sorting of threads (you can change this in your forum account settings) where I explained this specific Kernel Panic:

MacBook Pro M4 Pro (24GB/512GB) stuck in … - Apple Community

My device is a MacBook Air M4 10+256G. Analysis of the error message using DeepSeek and ChatGPT indicates that the restart is caused by a PCIe/SSD disconnection. However, I cannot determine the specific cause.

The SSD is disappearing from the bus. 99% of the time it is due to the SSD's controller no longer communicating with the rest of the system. This is the most common type of SSD failure for any SSD. You won't get more specific than this.

Taking it to an Apple authorized service center was also unsuccessful in diagnosing the problem. The staff suggested replacing the motherboard, but my device is less than a month old. I cannot accept the need to replace the motherboard on a brand new machine.

I'm actually surprised Apple was willing to replace the Logic Board so easily.....usually intermittent Kernel Panics require a lot of back & forth with Apple before they are willing to perform a hardware repair. Jump at the chance to get your laptop repaired before another tech wants to have you jump through tons of hoops.

Things fail....some sooner, others later. Many times you will never really know why something failed. It just happens. This is what the manufacturer's product warranty is for.....to deal with any product failures due to natural causes. Be grateful it occurred under warranty and not just after the warranty expired.

中文在下方⬇️

I also encountered this problem. I activated it on October 18th, so it's been activated for about 25 days. Four days ago, it suddenly crashed and restarted. After restarting, I checked the problem report and got the following:

panic(cpu 0 caller 0xfffffe00398e6250): ANS2 Recoverable Panic - assert failed: [14510]:apcie0[0]: Unexpected link down linksts=0x83000204 pcielint=0xf0017000, ltssm=0x00(DETECT_QUIET) - power(14)

My device is a MacBook Air M4 10+256G. Analysis of the error message using DeepSeek and ChatGPT indicates that the restart is caused by a PCIe/SSD disconnection. However, I cannot determine the specific cause. Taking it to an Apple authorized service center was also unsuccessful in diagnosing the problem. The staff suggested replacing the motherboard, but my device is less than a month old. I cannot accept the need to replace the motherboard on a brand new machine.

我也发生了这种状况，10月18号激活的，到今天差不多激活了25天。4天前突然出现死机-重启的状况，重启后查看问题报告，得到下面内容：

panic(cpu 0 caller 0xfffffe00398e6250): ANS2 Recoverable Panic - assert failed: [14510]:apcie0[0]: Unexpected link down linksts=0x83000204 pcielint=0xf0017000, ltssm=0x00(DETECT_QUIET) - power(14)

我的设备是macbook air m4 10+256G。通过把报错信息给deepseek与chatgpt分析得到是PCIe与ssd断链导致的重启。但我无法得知具体发生了什么。送到apple授权售后店铺也无法检测问题。工作人员给出建议让我更换主板，但我的设备购买一个月不到。我无法接受新机器就需要更换主板。

Put you kernel log to ChatGPT and you will get the excessive answer. If you seen this kernel trap before, the most likely this is HW issue.

Hi brother @cenzowm， I'm Chinese. I bought this computer 25 days ago, less than a month ago, and this problem has already appeared.

I'm currently communicating with Apple customer service, but the progress is quite slow; it might take two days to get a reply. It's really frustrating to encounter such a problem.

I found your post by searching keywords online, which made me realize that I might not be the only one experiencing this issue. Thank you for your post; it made me feel less helpless.

You are welcome.

Very fortunate it was hassle free.

Thanks for the update, hopefully it will help others as well.