I had a laptop running 16.04 for some time, and it served me well while traveling. I just pulled it out again after not using it for about a year, and on booting it reminded me "Hey jerk, 18.04 has come out since I last booted, time to update!" This sounded very reasonable to me and I tried to do so. The update went through the night, and stalled out somewhere along the way while installing packages. With no other options available, I made mistake #1, and killed the power.

Obviously this was the wrong choice, as I couldn't boot into the OS after doing that. No big deal, I figured, I'll just make a bootable thumb drive and install fresh. And so I did, and so I tried to do. This may or may not have been mistake #2.

Which leads us to now. Any attempt to install, either upon connecting to a wireless network or choosing to continue without connecting to one, leads directly to a never ending high speed list of what appears to be the same or very similar errors, going by too quickly to read in full, but I can catch the beginning"

"pcieport 0000:00:1c.5".

As it kindly counts the errors for me, I can see that it's counted up over 700 million in the time it took me to write this post, with no sign of stopping. I can run directly off the bootable thumb drive, so if there are any solutions available, I am all ears.

Edit1: Thanks to guiverc's suggestion to add a boot parameter, the install no longer explodes in a shower of errors. Instead though, it hangs endlessly at the sane point, or earlier. Sometimes I get as far as choosing whether or not to connect to wifi, sometimes only as far as selecting my keyboard layout. But it always hangs.

Edit2: Solution found! Although I never successfully stopped the stream of PCI-bus errors, I was able to make it through the installation by stopping the Rsyslog service before starting it. This is at best a workaround and not a proper fix, and still leaves me stuck disabling Rsyslog to prevent the billions of errors from being logged and filling my drive, but at this point, I'll take it.