Trouble installing LinuxCNC on Raspberry Pi

Hi everyone,

I'm trying to do my first install on my Raspberry Pi 4 with EtherCAT. I'm having trouble pretty early in the install process. I'm following what to do from this page
forum.linuxcnc.org/ethercat/42048-notes-...at-on-raspberry-pi-4

Any thoughts on how to fix this? Thanks!

What I'm doing:

1. Download  www.linuxcnc.org/iso/linuxcnc-2.8.1-pi4.zip 
2. I image the SD card with 
    - Balena Etcher -or-
    - "Writing the image to a USB storage device in Mac OSX" from the above link
    - Both methods demonstrate the same problem
3. Setup ssh, wpa_config.conf
4. Insert SD card, start RPi
5. SSH in and:
6. Change password
7. sudo apt update -- seems to go ok
8. sudo apt upgrade -- this is where the problems happen. Snippets of output below. Interesting stuff in bold.

...
<snip>
Leaving 'diversion of /boot/./bcm2835-rpi-b.dtb to /usr/share/rpikernelhack/./bcm2835-rpi-b.dtb by rpikernelhack'
Leaving 'diversion of /boot/./bcm2835-rpi-b-rev2.dtb to /usr/share/rpikernelhack/./bcm2835-rpi-b-rev2.dtb by rpikernelhack'
Leaving 'diversion of /boot/./bcm2835-rpi-a.dtb to /usr/share/rpikernelhack/./bcm2835-rpi-a.dtb by rpikernelhack'
Unpacking linux-image-4.19.71-rt24-v7l+ (4.19.71-rt24-v7l+-4) over (4.19.71-rt24-v7l+-1) ...
dpkg: error processing archive /tmp/apt-dpkg-install-ez4FUH/156-linux-image-4.19.71-rt24-v7l+_4.19.71-rt24-v7l+-4_armhf.deb (--unpack):
unable to make backup link of './boot/System.map-4.19.71-rt24-v7l+' before installing new version: Operation not permitted
dpkg-deb: error: paste subprocess was killed by signal (Broken pipe)
Preparing to unpack .../157-linuxcnc-doc-en_1%3a2.8.4_all.deb ...
Unpacking linuxcnc-doc-en (1:2.8.4) over (1:2.8.1) ...
Preparing to unpack .../158-python-pil.imagetk_5.4.1-2+deb10u3_armhf.deb ...
Unpacking python-pil.imagetk:armhf (5.4.1-2+deb10u3) over (5.4.1-2+deb10u2) ...
...<snip>
Unpacking wpasupplicant (2:2.7+git20190128+0c1e29f-6+deb10u3) over (2:2.7+git20190128+0c1e29f-6+deb10u2) ...
Errors were encountered while processing:
/tmp/apt-dpkg-install-ez4FUH/156-linux-image-4.19.71-rt24-v7l+_4.19.71-rt24-v7l+-4_armhf.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)8.

If I reboot, I cannot ssh in any longer.

 

I was trying to stay to the documentation in the link I attached, as it's my first time trying out LinuxCNC. But if this doesn't bother you, I'll move forward without the upgrade and leave quibbles for after I've kicked the tires. Thanks for looking at this.

You should install the new version as shown here
buildbot.linuxcnc.org/