404 Client Error: Not Found ('no such image: homeassistant/...)
This error indicates the image, whether for updating to Home Assistant or installing or updating an add-on, was not able to be pulled to your system. This is usually a situation where there is not enough space for the image to be downloaded. The first thing to check for is the available space on your system.
Please note, if you are running the operating system as a virtual machine; the default VM image is only about 6GB. Many VM users run into this as they have not allocated enough storage. 32GB is the minimum recommended size.
You will need to explore your own system to determine where space has gone.
df -h in the SSH add-on console to you can quickly check to see if you have space available.
If there is plenty of space available then you might check to see if you are having network issues that are preventing images from being downloaded.