Hi All,

I've checked the forums before posting, and I'm not seeing others report this symptom yet. I have UnRAID running on a Mac mini and it's been working really well for the past few years.

It's currently running 7.14 and using an Kingston USB (one of the 'known working' / recommended ones). I attempted to upgrade to 7.2 last night and after it wouldn't boot with a kernel panic and warmings about /dev/root / can't open block device.

From various reading this is usually an issue with the USB stick, or damaged file system. I copied the previous bz files back to the root of the USB and it's booting correctly now (back to 7.14).

As a troubleshooting step, I grabbed a seperate (and admittedly older) Mac Mini and a different USB stick (Verbatim) and did a fresh/vanilla install of 7.2. The attached error is the same on the PROD UnRaid Mac Mini (noting PROD is a Macmini6,2 with a Kingston USB), but apart from that difference the kernel panic and error is the same.

Any suggestions welcome, and/or is there some difference with 7.2 which is preventing it from working on the Mac Minis now?

Try recreating the flash drive, first backup the current one, then recreate it using the USB tool, confirm the flash drive boots with the stock install, and if yes, restore only the /config folder from the backup overwriting any existing files.

Thank you for that suggestion and I tried a variation of that. I grabbed a new/clean flash drive and used the USB created tool to make a new/vanilla one. Exact same error (that’s where the screen shot is from).

I missed it was a Mac, possibly some kernel compatibility issue.

I guess I’ll wait for the next update and see if it’s resolved. I’ve been running this happily for years, and it’s worked really well.

Same here with a Mac Mini Mid 2011 and a Sandisk Ultra USB-Stick. Downgrade to 7.1.4 works just fine.

I've seen a few reports of this happening with Macs and 7.2.0, so likely some kernel compatibility issue. It's not the first time this has happened with Apple hardware, e.g.: https://forums.unraid.net/topic/120271-692-crashes-on-boot-kernel-panic-not-syncing-vfs-unable-to-mount-root-fs-on-unknown-block00/

They can be tricky since they use a UEFI implementation that’s technically compliant but behaves differently, best bet is to remain on 7.1 for now and then try 7.3, the first beta should be out in a couple of months, and that is expected to have a completely different kernel.

Thank you for providing some hope. I’ll try again with the next release.

Does anyone know if 7.2.1 fixes this issue?

I've not had a chance to test yet, but looking at the release notes I don't see anything about this bug, and the kernel doesn't look to be changed so I'm assuming this update won't fix this.

Kernel is the same, but it's worth a try just in case, there's an Intel microcode update; maybe that could help.

Okay, just did a quick test by downloading 7.2.1 onto a test USB stick and trying it in a Mac mini 2012. Still getting the kernel panic.

11 minutes ago, James Miller said:

Okay, just did a quick test by downloading 7.2.1 onto a test USB stick and trying it in a Mac mini 2012. Still getting the kernel panic.

Thanks for giving it a go!

Thanks for testing, kind f expected, but still worth a try, 7.3-beta should be out very soon, and is expected to have kernel 6.17 or 6.18 (if already out).

BTW, are you guys booting UEFI or legacy? I tested before with a late 2012 Mac mini and could reproduce the issue, it had OpenCore Legacy Patcher installed, and I only saw the UEFI option.

I've since reformatted it without OpenCore, and UEFI boot doesn't even start, but legacy works with 7.2.1

That's a fair question to ask. I'm using UEFI boot (not legacy), and these Macs have never had OCLP on them. I hadn't thought to try legacy boot as I've not needed to do that before. I'll get it a try on the test Mac and see if I get different results.

It may also be worth checking the BIOS/firmware version. I noticed that mine is fairly recent; I suspect it was just updated when I installed the latest supported macOS and all the updates, which in my case is Catalina.

BTW, did a little more testing, and it doesn't appear to be the firmawre, just legacy vs UEFI boot.

As I mentioned, my Mac Mini had OCLP installed, and during boot with that, it automatically showed the Unraid boot option without pressing the boot menu key:

And that failed the same way as reported in this thread:

After I restored the Mini to use the latest supported macOS without the patcher, I had to press the boot selection key, and there are 3 options:

For some reason, the EFI boot option is not working now; it locks up on that screen, doesn't show anything else, but choosing the Windows option, it boots legacy, and it can boot 7.2.x fine. This is the part where it crashes during UEFI boot:

Boot complete:

So worth testing for anyone else having the same issue, if legacy boot still works.

On 11/23/2025 at 12:06 AM, JorgeB said:

So worth testing for anyone else having the same issue, if legacy boot still works.

@JorgeB Do you have any information on how to switch between Legacy boot and EFI boot?

There are a couple of ways.

On the Mac Mini if you hold down the OPTION key on boot it will list the various boot options. You should see an EFI and a legacy boot option. You can then select the non EFI option to legacy boot.

Also from within UnRAID -> MAIN -> flash (boot device) then down the bottom there is a "Permit UEFI boot mode". If you turn that off it forces legacy boot.

Hi,

I think I forgot to report back after the previous testing. The Mac Minis I'm using all have the most recent firmware they can, and non have had OCLP on them.

I did try using legacy boot, and UnRAID itself would boot but if I had the external Thunderbolt enclosures attached the Mac Mini would hang on LEGACY boot with the newer OS.

So, I've stuck with 7.1.4, using EFI boot as that's the combo that works.

I'm hoping the next major release will fix the fault and allow me to upgrade.

J

Just found that my 2012 Mac mini can boot in UEFI mode with 7.2.4 using the Limine bootloader, so it may also work for others affected. It's worth a try:

https://forums.unraid.net/topic/196349-black-screen-after-usb-boot-msi-x870e-carbon-ryzen-9950x-rtx-4070-ti-super/#findComment-1607672

I’ve been testing this tonight and appears to work. Able to boot the Mac Mini 2012, in EFI mode with the Thunderbolt 2 enclosures attached.

@James Miller did you just use the config settings posted above? I have a mini with this issue too.

3 hours ago, RimuJim said:

I have a mini with this issue too.

The posted config is an example; you can adapt it to the options you are using, but that one will work as is.