PR4100 Firmware Update Bricked my Unit Update to my earlier post PR4100 displays welcome to wd my cloud pr4100 and flashing blue light after latest firmware update

After working with WD support, it is official, my PR4100 is dead after trying to install the latest firmware update when I was prompted. The unit said an update was available, I think it was 2.41.116, it ran as usual, went to restart and the result was a flashing blue light on the power button. The unit was on a APC UPS so I know it was not a power issue. After hours of working through it using support chat, I was told to replace the unit. During these conversations when I stated the unit was fine pre-firmware update and only died after the update process, it fell on deaf ears. In fairness to WD, this was a 2 year old warranty replacement for a DL4100 that failed with critical warnings after 3 years of use. The replacement carried a 90 day warranty. Now I am in the process of working to recover the data off the drives using Ubuntu. The easy way would be to buy a new unit, pop the drives in, and I would be back up. My experience on this is a 2 to 3 year life cycle on one of these units, a very disappointing and costly experience. And an experience which I can’t justify continuing.

I wondered how long it might be before something like this happened.

Thanks for the reply and info. I was told by a WD level 2 tech the unit cannot be reprogrammed, as in the usb port cannot be used. I used xenix / linux 30 years ago and have not since, until I started playing around with Ubuntu a few days ago. Initially the process seems both doable and yet difficult. I’m starting to look at doing it. I started this response yesterday and forgot to send it.

Just read your last response and says you withdrew an earlier post. Is that correct? Reading your last post I was going to attempt it. If I understand your update, you are now saying it is bricked, or do I misunderstand?

So it looks like something happened during the update that wasn’t a power failure since it was on the UPS. On its restart after the update the power light was flashing and the unit was unreachable via Ethernet. This is really frustrating and I question how ethical WD has been on it with me. In your opinion, do you think there is any further recourse with WD?

Thanks Bruce

I didn’t notice your last reply, sometimes the forum doesn’t notify me. Yes, I sometimes withdraw or delete posts to keep down the clutter, which makes it easier for me to find things. My post to your thread probably got removed by mistake.

Here’s the information I posted previously. Let me know if you can boot the PR4100, and if so, I may be able to help you bring it back to life.

Hi dswv42,
Thanks for the response. Today I was able to create a bootable usb stick. I have gotten into the pr4100, installed a couple drives and established a raid 1. I could use help getting the system booting from firmware on the PR4100 by using ssh. I haven’t used ssh before, so I need to learn it all.
Thanks in advance

If you were able to boot the PR4100 from USB, it’s definitely not bricked and recovery should be very easy. Here’s a link to a zip file which contains the PR4100 rescue (Safe Mode) firmware. Simply download the zip file and extract it’s contents to a blank USB flash drive.

Afterwards, download the firmware for the PR4100 from the WD website and save it to your computer.


Power off the PR4100, remove all hard drives, then insert the USB flash drive and power it on again. Give it time to finish booting into “Safe Mode”, then connect to it via a web browser using the IP address. A “Safe Mode” firmware upload page should become available, where you can manually upload the firmware.

CAUTION: Remove the USB flash drive prior to uploading new firmware, or it will boot from the flash drive when it reboots. If you have trouble uploading new firmware, try a different browser.


After uploading the firmware and the PR4100 has finished rebooting, power it off again and reinsert the hard drives, before powering it on again.

I created the usb stick with the downloaded rescue file, and I’ve tried twice using chrome, and once with Microsoft edge. After each process reboots the screen on the pr4100 says “Firmware update failed”.

At what point in the process do I remove the usb drive?
Feels so close.

I’m afraid that’s the result of bad instructions on my part. I was distracted and left out one important step. Remove the USB flash drive just before uploading new firmware using the browser. The rescue firmware runs from RAM, and this prevents it from booting from the USB flash drive when it reboots. The “Firmware update failed” message originates from the rescue firmware. It’s programmed to say that, regardless.

At this point, there should be no need to load the firmware again, as it probably installed fine after the first attempt. Simply remove the USB flash drive and reboot by holding the power button until it shuts off, then power it on again to boot normally.

Not quite there. When it comes back up the display on the pr4100 looks ok. When I try to log into it at the ip address I get the following.

Safe Mode

Your device firmware appears to be corrupted and your device is currently running in Safe Mode.

Please download the latest firmware from the WD Support website at http:\ and upload the firmware file below:

Firmware Version:
Upload File:

Do I download the software from the wd site and try it again?

Yes. Something may have happened during the previous attempts, and now it’s booting from the internal rescue firmware, which is identical to the rescue firmware on USB, except that I altered the bootloader config file so it would boot from USB.

If the same thing happens again, an eMMC partition may be damaged, but I know how to repartition and format it if needed.

Pulled the firmware off the wd site, went through the process again, ending with the same result. When it reboots and I log in via chrome it is back on the safe mode screen, prompting me to upload firmware.

I was afraid of that. Something is probably wrong with the eMMC flash partitions, possibly corruption, but I can’t be sure. The factory firmware is supposed to check the eMMC partitions, but there’s a bug in a boot script (found by me) that wasn’t corrected until they released OS5, but it’s of no help here.

I know how to check eMMC and even re-partition and format it if needed, but there’s a problem… courtesy of WD and their developers. The factory firmware doesn’t appear to have SSH enabled, or at least it’s not working when I test it. That, plus some of the required Linux programs don’t appear to be present.

Don’t worry, all hope is not lost, but it may take a little time for me to put something together that you can use to figure out what’s going on. I’ve been meaning to create new rescue firmware with the proper tools available, but have been working on other projects.

In the mean time, there is a way, but it’s a little complicated. Basically, you can use a preseeded Debian installer to get an SSH connection to figure out what’s going on. It’s a workaround, but it should do the trick. Let me know and I will see what I can do.

First off, I sincerely appreciate your help and time on this, and when you decide its toast, I will accept that. I will do what ever you ask in performing tasks on this. Depending on what they are, I will need direction. As for taking time, your helping me, and I respect you will attempt to work on it if and when you have time.

Thanks again. Bruce

It’s not a problem, and I know the PR4100 extremely well. If it can be saved, I can save it. One thing I need to know, are you a Mac user? If so, do you also have a Windows computer? The ISO to USB tool I use requires windows.

By the way, I tested the Debian installer process I mentioned, and everything needed is there.

These are quick and dirty instructions. They aren’t pretty, but they should get the job done. Despite it being a Debian installer, it can be used to a establish an SSH connection and use repair tools, without installing anything.

Download the Debian 9 Netinst ISO:


Download Rufus Portable (Windows Only):


Or download a suitable ISO to USB tool if you’re a Mac user.

Use Rufus (or a suitable ISO to USB tool) to copy the Debian ISO file to the USB flash drive using ISO mode. After the ISO to USB process has finished, edit \boot\grub\grub.cfg on the USB flash drive and replace its contents with the following.

set default="0"
set timeout="5"

menuentry --hotkey=i 'Debian Preseed Install' {
    linux    /install.amd/vmlinuz debian-installer/locale=en_US keyboard-configuration/xkb-keymap=us preseed/file=/cdrom/preseed.cfg console=ttyS0,115200n8
    initrd   /install.amd/initrd.gz
submenu 'Advanced options ...' {
    menuentry --hotkey=e '... Expert install' {
        linux    /install.amd/vmlinuz priority=low console=ttyS0,115200n8
        initrd   /install.amd/initrd.gz
    menuentry --hotkey=r '... Rescue mode' {
        linux    /install.amd/vmlinuz rescue/enable=true console=ttyS0,115200n8
        initrd   /install.amd/initrd.gz

Create a preseed.cfg file using the following and save it to the root of the USB flash drive.

### Preseed (Manual SSH Install):

d-i debian-installer/splash boolean false
d-i debian-installer/locale string en_US
d-i keyboard-configuration/xkb-keymap select us
d-i netcfg/choose_interface select auto
d-i netcfg/get_hostname string unassigned-hostname
d-i netcfg/get_domain string unassigned-domain
d-i netcfg/wireless_wep string
d-i ethdetect/prompt_missing_firmware boolean false
d-i hw-detect/load_firmware boolean true
d-i anna/choose_modules string network-console
d-i network-console/password password r00tme
d-i network-console/password-again password r00tme
#d-i network-console/authorized_keys_url string

Remove the USB flash drive and insert it into the NAS, then briefly press the power button to power it on. It may take up to 5 minutes to provide an SSH connection. The default login during the manual SSH install process is (username: installer / password: r00tme).

Once an SSH connection is established, give the Debian installer time to build the root filesystem, then use the down arrow key to select “Start Shell” then press enter, then press enter again to select “Continue”. you should now have a command prompt.

Execute the following commands, one at a time, to test the internal eMMC flash partitions and repair common filesystem errors if needed. The first command may say “CP437: Invalid argument”, but you can safely ignore it.

fsck.fat -p /dev/mmcblk0p1
e2fsck -p /dev/mmcblk0p2
e2fsck -p /dev/mmcblk0p3
e2fsck -p /dev/mmcblk0p4
e2fsck -p /dev/mmcblk0p5
e2fsck -p /dev/mmcblk0p6
e2fsck -p /dev/mmcblk0p7
e2fsck -p /dev/mmcblk0p8
e2fsck -p /dev/mmcblk0p9

Execute the following command, and post the output.

blkid -o list

Now you can shut down the NAS and remove the USB flash drive. Power it on and try the “Safe Mode” firmware install process again. If this fails, we can take more extreme measures.

I’ve revised the “Debian installer” SSH instructions posted previously to make them more clear, so be sure to read them on the forum to see the changes.