Yes, those errors are “normal”, but they are not indicating a hardware issue. I’ve been writing a blog post to explain exactly that since June 27th, but I keep getting distracted with other things to do, then I continue writing the blog post, then distracted again, etc… (and you all know how detailed/verbose I like to be in my blog posts).
But to summarize the issue : there is some undocumented magical setting that needs to be set on the SATA controller to prevent these link errors in SATA communications. I have been unable (so far, but still looking) to find what it is, but I have a workaround for it in coreboot so the issue doesn’t affect grub at least (https://github.com/kakaroto/coreboot/commit/a841e79238aa8a284ac06bda9a1500f6f00fe409).
The thing though is that the issue only happens when the SATA drive is configured to work on 6gbps speeds, and when the errors happen, the linux kernel will automatically retry, if it succeeds to read when it retries, then it continues, until there’s another error, then it retries the read, etc… if when it retries the read, it’s unable to read the data a second time, then it drops the connection speed to 3Gbps, and that will completely stop any errors and the SATA works just fine at 3Gbps speeds (that’s why you sometimes see only 1 error, sometimes 3, sometimes 20… but you’ll always notice that the last ‘ata’ message in dmesg before the errors stopped was about the speed being changed to 3gbps).
So anyways, that’s how it is. Hopefully I’ll be able to finish my first draft of the blog post sometime this week, then it will go through a couple of revisions and i’ll post it so you can understand in more details what exactly is behind this issue, but to summarize things : it is nothing to be worried about, the errors are recovered by the linux kernel automatically, if not, then speed drops to 3gbps in which case the errors disappear entirely.
As for the original post here, it looks to me like it has something to do with the encryption password. I have no idea why your machine rebooted on its own (was the battery low?) but it looks like your install doesn’t find the encrypted partition or it can’t decrypt it (wrong password?) or maybe something caused it reboot at the wrong time and it corrupted your partition… I have no idea, but the "volume group ‘crypt’ not found’ sounds like it… although it then says it found 2 logical volumes in the group ‘crypt’, and says that cryptsetup was set up successfully (which means the password is correct I think, but i’m not much of an expert on that area)…
as for the “failed to load firmware”, you can ignore it, the GPU can have an optional firmware loaded into it that slightly increases performance, but since PureOS is a binary free OS, it does not come with the proprietary firmware for the graphics card (i915 is the graphics driver) but it won’t affect the ability to use the GPU. I think there should be another similar warning about the bluetooth driver missing, that one is mandatory for bluetooth to work, so without it, there is no bluetooth support in PureOS, but it’s irrelevant to your issue as well.