I'm trying to install Ubuntu Core version 18 on my Raspberry Pi 2 model B. I've followed this official tutorial an I've mounted the image on the SD card by using Balena Etcher. When I try to turn on the Raspberry, the screen remains black and the status led blinks 7 times meaning that the kernel hasn't been found in the SD card. I've tried using different SD card (of different size), different power suppliers for the board but nothing has changed. I've also tried to mount th SD on ubuntu by using the Disks utility instead of Balena Etcher with no success. Other ditribution (like the official Raspbian) boots fine. How can I proceed to investigate on this problem? Thanks in advance.
1 Answer
It appears your download of the image may have been corrupted perhaps. We can try an alternate method of ensuring the image is successfully downloaded. There is a download tool in the archive called aria2 that you can install. The advantage over wget is that it will not just download the file for you but also compare its checksum to verify if anything is lost in transmission.
At the Ubuntu Core installation instructions for a Raspberry Pi 2, we find a link to the image as well as a link to the SHA256 checksum. You'll want to pick from the list the checksum that corresponds to the image file being downloaded. Assuming you've installed aria2 as suggested above you can use those pieces of information to download the image.
An example of invoking aria2 would look like:
aria2c --checksum=sha-256=9e370188c663afcdbcb62d30b1964ac838c7ecffc53eac360ed840b5c20abf12
As part of the program output when the download completes you should see included the following text:
Verification finished successfully.
That will indicate you receive the file without any corruption in the download process. If you don't get that response you need to see if you are having problems with your connection to the Internet perhaps. While such problems can be rare they do occur from time to time.
If you don't want to use that particular download tool, you can run on the command line the following:
sha256sum ubuntu-core-18-armhf+raspi2.img.xz
It should provide the following output that you would compare against what was posted on the site linked above:
9e370188c663afcdbcb62d30b1964ac838c7ecffc53eac360ed840b5c20abf12 ubuntu-core-18-armhf+raspi2.img.xz
Good luck in trying to download again.
