# Mender-convert'ed image fails to boot, can't mount root
**URL:** https://hub.mender.io/t/mender-converted-image-fails-to-boot-cant-mount-root/2947
**Category:** General Discussions
**Created:** [December 7, 2020, 6:24pm UTC](https://hub.mender.io/t/mender-converted-image-fails-to-boot-cant-mount-root/2947 "2020-12-07T18:24:56Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@dgiambo1](https://hub.mender.io/u/dgiambo1)
#### Post date: [December 7, 2020, 6:24pm UTC](https://hub.mender.io/t/mender-converted-image-fails-to-boot-cant-mount-root/2947/1 "2020-12-07T18:24:57Z")
I’m having trouble using Mender-convert on an existing RPI4 image. The image uses a custom kernel, so I run mender-convert like this:
sudo MENDER\_ARTIFACT\_NAME=alpha-1 ./docker-mender-convert --disk-image input/golden-image.img --config configs/raspberrypi4\_config --overlay rootfs\_overlay\_alpha\_1/
And then I manually replace the kernel7l.img with my custom one, which does have CONFIG\_FHANDLE set.
The image will now boot partially, it stops at this output:
Waiting for root device ${mender\_kernel\_root}…
Later I see the mmc come up but it looks like uboot never expanded ${mender\_kernel\_root} before passing it to the kernel… What am I missing?
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### Author:  [@drewmoseley](https://hub.mender.io/u/drewmoseley)
#### Post date: [December 7, 2020, 7:58pm UTC](https://hub.mender.io/t/mender-converted-image-fails-to-boot-cant-mount-root/2947/2 "2020-12-07T19:58:21Z")
With mender-convert, the kernel\*.img file is actually U-Boot which then loads the kernel from the active root filesystem. You probably need to put your updated kernel in the /boot directory of each of the root filesystem partitions.
Drew
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### Author:  [@dgiambo1](https://hub.mender.io/u/dgiambo1)
#### Post date: [December 7, 2020, 8:54pm UTC](https://hub.mender.io/t/mender-converted-image-fails-to-boot-cant-mount-root/2947/3 "2020-12-07T20:54:49Z")
That makes a whole lot of sense, that way the filesystem update can contain a new kernel.
Unfortunately, even if I replace both rootfs partitions /boot/zImage with my custom kernel, and leave the boot partition image unchanged from what mender-convert generates, I don’t get a working boot. I’m not sure where to look next because there is no output despite a loglevel=7 after the bootloader, just black screen.
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### Author:  [@dgiambo1](https://hub.mender.io/u/dgiambo1)
#### Post date: [December 7, 2020, 9:05pm UTC](https://hub.mender.io/t/mender-converted-image-fails-to-boot-cant-mount-root/2947/4 "2020-12-07T21:05:43Z")
I assume I need device tree binaries and overlays as well? I tried putting those in the same directory, but no luck.
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### Author:  [@mirzak](https://hub.mender.io/u/mirzak)
#### Post date: [December 8, 2020, 7:14am UTC](https://hub.mender.io/t/mender-converted-image-fails-to-boot-cant-mount-root/2947/5 "2020-12-08T07:14:24Z")
I think it is best to verify with known working configurations, e.g
> [@Raspberry Pi 4 Model B + Raspbian](https://hub.mender.io/t/raspberry-pi-4-model-b-raspbian/1312):
>
> Board description The speed and performance of the new Raspberry Pi 4 is a step up from earlier models. For the first time, we’ve built a complete desktop experience. Whether you’re editing documents, browsing the web with a bunch of tabs open, juggling spreadsheets or drafting a presentation, you’ll find the experience smooth and very recognisable — but on a smaller, more energy-efficient and much more cost-effective machine. [image] URL: [https://www.raspberrypi.org/products/raspberry-pi-4-mo…](https://www.raspberrypi.org/products/raspberry-pi-4-model-b)
And trace from there any customization you need to make.