I tried to reproduce the issue and found it is an "unsupport platform" for the tool flash-kernel
ubuntu@ubuntu:~$ dpkg -l *1044* Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name Version Architecture Description +++-===================================================-==============================-==============================-============================================================================================================ ii linux-headers-4.15.0-1044-raspi2 4.15.0-1044.47 armhf Linux kernel headers for version 4.15.0 on ARM (hard float) SMP ii linux-image-4.15.0-1044-raspi2 4.15.0-1044.47 armhf Linux kernel image for version 4.15.0 on ARM (hard float) SMP ii linux-modules-4.15.0-1044-raspi2 4.15.0-1044.47 armhf Linux kernel extra modules for version 4.15.0 on ARM (hard float) SMP ii linux-raspi2-headers-4.15.0-1044 4.15.0-1044.47 armhf Header files related to Linux kernel version 4.15.0 ubuntu@ubuntu:~$ sudo apt-get install --reinstall linux-headers-4.15.0-1044-raspi2 linux-image-4.15.0-1044-raspi2 linux-modules-4.15.0-1044-raspi2 linux-raspi2-headers-4.15.0-1044 Reading package lists... Done Building dependency tree Reading state information... Done 0 upgraded, 0 newly installed, 4 reinstalled, 0 to remove and 0 not upgraded. 1 not fully installed or removed. Need to get 0 B/44.6 MB of archives. After this operation, 0 B of additional disk space will be used. (Reading database ... 113356 files and directories currently installed.) Preparing to unpack .../linux-image-4.15.0-1044-raspi2_4.15.0-1044.47_armhf.deb ... Unpacking linux-image-4.15.0-1044-raspi2 (4.15.0-1044.47) over (4.15.0-1044.47) ... Preparing to unpack .../linux-headers-4.15.0-1044-raspi2_4.15.0-1044.47_armhf.deb ... Unpacking linux-headers-4.15.0-1044-raspi2 (4.15.0-1044.47) over (4.15.0-1044.47) ... Preparing to unpack .../linux-modules-4.15.0-1044-raspi2_4.15.0-1044.47_armhf.deb ... Unpacking linux-modules-4.15.0-1044-raspi2 (4.15.0-1044.47) over (4.15.0-1044.47) ... Preparing to unpack .../linux-raspi2-headers-4.15.0-1044_4.15.0-1044.47_armhf.deb ... Unpacking linux-raspi2-headers-4.15.0-1044 (4.15.0-1044.47) over (4.15.0-1044.47) ... Setting up linux-raspi2-headers-4.15.0-1044 (4.15.0-1044.47) ... Setting up linux-modules-4.15.0-1044-raspi2 (4.15.0-1044.47) ... Setting up flash-kernel (3.90ubuntu3.18.04.2) ... Setting up linux-headers-4.15.0-1044-raspi2 (4.15.0-1044.47) ... Setting up linux-image-4.15.0-1044-raspi2 (4.15.0-1044.47) ... Processing triggers for linux-image-4.15.0-1044-raspi2 (4.15.0-1044.47) ... /etc/kernel/postinst.d/initramfs-tools: update-initramfs: Generating /boot/initrd.img-4.15.0-1044-raspi2 flash-kernel: deferring update (trigger activated) /etc/kernel/postinst.d/zz-flash-kernel: flash-kernel: deferring update (trigger activated) Processing triggers for flash-kernel (3.90ubuntu3.18.04.2) ... Unsupported platform. dpkg: error processing package flash-kernel (--configure): installed flash-kernel package post-installation script subprocess returned error exit status 1 Errors were encountered while processing: flash-kernel E: Sub-process /usr/bin/dpkg returned an error code (1) ubuntu@ubuntu:~$ flash-kernel Unsupported platform. ubuntu@ubuntu:~$ sudo flash-kernel Unsupported platform. ** Also affects: flash-kernel (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-raspi2 in Ubuntu. https://bugs.launchpad.net/bugs/1841955 Title: Can't upgrade kernel on raspberry pi3a+ Status in flash-kernel package in Ubuntu: New Status in linux-raspi2 package in Ubuntu: New Bug description: Can't upgrade kernel on raspberry pi3b+ [Steps to Reproduce] 1. dd the image in an SD card: http://cdimage.ubuntu.com/ubuntu/releases/18.04/release/ubuntu-18.04.3-preinstalled-server-armhf+raspi3.img.xz 2. Boot rpi3a+ with the sd card 3. Upgrade the kernel using following command: sudo apt update sudo apt install linux-raspi2 4. Check output message [Expected Result] Current stable kernel(4.15.0-1043-raspi2) is installed. [Actual Result] Error shows up during the installation, and the kernel is still the original one after reboot. [Additional Info] Command output: ubuntu@ubuntu:~$ sudo apt install linux-raspi2 Reading package lists... Done Building dependency tree Reading state information... Done The following additional packages will be installed: linux-headers-4.15.0-1043-raspi2 linux-headers-raspi2 linux-image-4.15.0-1043-raspi2 linux-image-raspi2 linux-modules-4.15.0-1043-raspi2 linux-raspi2-headers-4.15.0-1043 Suggested packages: fdutils linux-raspi2-doc-4.15.0 | linux-raspi2-source-4.15.0 linux-raspi2-tools The following NEW packages will be installed: linux-headers-4.15.0-1043-raspi2 linux-image-4.15.0-1043-raspi2 linux-modules-4.15.0-1043-raspi2 linux-raspi2-headers-4.15.0-1043 The following packages will be upgraded: linux-headers-raspi2 linux-image-raspi2 linux-raspi2 3 upgraded, 4 newly installed, 0 to remove and 16 not upgraded. Need to get 45.1 MB of archives. After this operation, 214 MB of additional disk space will be used. Do you want to continue? [Y/n] Get:1 http://ports.ubuntu.com/ubuntu-ports bionic-updates/universe armhf linux-raspi2-headers-4.15.0-1043 armhf 4.15.0-1043.46 [11.0 MB] Get:2 http://ports.ubuntu.com/ubuntu-ports bionic-updates/universe armhf linux-headers-4.15.0-1043-raspi2 armhf 4.15.0-1043.46 [852 kB] Get:3 http://ports.ubuntu.com/ubuntu-ports bionic-updates/universe armhf linux-modules-4.15.0-1043-raspi2 armhf 4.15.0-1043.46 [26.5 MB] Get:4 http://ports.ubuntu.com/ubuntu-ports bionic-updates/universe armhf linux-image-4.15.0-1043-raspi2 armhf 4.15.0-1043.46 [6,751 kB] Get:5 http://ports.ubuntu.com/ubuntu-ports bionic-updates/universe armhf linux-raspi2 armhf 4.15.0.1043.41 [1,884 B] Get:6 http://ports.ubuntu.com/ubuntu-ports bionic-updates/universe armhf linux-image-raspi2 armhf 4.15.0.1043.41 [2,524 B] Get:7 http://ports.ubuntu.com/ubuntu-ports bionic-updates/universe armhf linux-headers-raspi2 armhf 4.15.0.1043.41 [2,512 B] Fetched 45.1 MB in 19s (2,363 kB/s) Selecting previously unselected package linux-raspi2-headers-4.15.0-1043. (Reading database ... 62492 files and directories currently installed.) Preparing to unpack .../0-linux-raspi2-headers-4.15.0-1043_4.15.0-1043.46_armhf.deb ... Unpacking linux-raspi2-headers-4.15.0-1043 (4.15.0-1043.46) ... Selecting previously unselected package linux-headers-4.15.0-1043-raspi2. Preparing to unpack .../1-linux-headers-4.15.0-1043-raspi2_4.15.0-1043.46_armhf.deb ... Unpacking linux-headers-4.15.0-1043-raspi2 (4.15.0-1043.46) ... Selecting previously unselected package linux-modules-4.15.0-1043-raspi2. Preparing to unpack .../2-linux-modules-4.15.0-1043-raspi2_4.15.0-1043.46_armhf.deb ... Unpacking linux-modules-4.15.0-1043-raspi2 (4.15.0-1043.46) ... Selecting previously unselected package linux-image-4.15.0-1043-raspi2. Preparing to unpack .../3-linux-image-4.15.0-1043-raspi2_4.15.0-1043.46_armhf.deb ... Unpacking linux-image-4.15.0-1043-raspi2 (4.15.0-1043.46) ... Preparing to unpack .../4-linux-raspi2_4.15.0.1043.41_armhf.deb ... Unpacking linux-raspi2 (4.15.0.1043.41) over (4.15.0.1041.39) ... Preparing to unpack .../5-linux-image-raspi2_4.15.0.1043.41_armhf.deb ... Unpacking linux-image-raspi2 (4.15.0.1043.41) over (4.15.0.1041.39) ... Preparing to unpack .../6-linux-headers-raspi2_4.15.0.1043.41_armhf.deb ... Unpacking linux-headers-raspi2 (4.15.0.1043.41) over (4.15.0.1041.39) ... Setting up linux-raspi2-headers-4.15.0-1043 (4.15.0-1043.46) ... Setting up linux-modules-4.15.0-1043-raspi2 (4.15.0-1043.46) ... Setting up linux-image-4.15.0-1043-raspi2 (4.15.0-1043.46) ... I: /boot/vmlinuz is now a symlink to vmlinuz-4.15.0-1043-raspi2 I: /boot/initrd.img is now a symlink to initrd.img-4.15.0-1043-raspi2 Setting up linux-headers-4.15.0-1043-raspi2 (4.15.0-1043.46) ... Setting up linux-image-raspi2 (4.15.0.1043.41) ... Setting up linux-headers-raspi2 (4.15.0.1043.41) ... Setting up linux-raspi2 (4.15.0.1043.41) ... Processing triggers for linux-image-4.15.0-1043-raspi2 (4.15.0-1043.46) ... /etc/kernel/postinst.d/initramfs-tools: update-initramfs: Generating /boot/initrd.img-4.15.0-1043-raspi2 flash-kernel: deferring update (trigger activated) /etc/kernel/postinst.d/zz-flash-kernel: flash-kernel: deferring update (trigger activated) Processing triggers for flash-kernel (3.90ubuntu3.18.04.2) ... Unsupported platform. dpkg: error processing package flash-kernel (--configure): installed flash-kernel package post-installation script subprocess returned error exit status 1 E: Sub-process /usr/bin/dpkg returned an error code (1) ubuntu@ubuntu:~$ To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/flash-kernel/+bug/1841955/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp