I know this question has been posted a bunch of times, but none of the cases seem to apply here. This started a few days ago and it's been a hassel to no end.
I have a Lenovo Thinkpad E480 (Intel i7-8550U) with both Windows 10 and Ubuntu 18.04 installed on an nvme0 samsung M.2 SSD, I also installed a second SSD on arrival, and was working fine for the last few months. A few days ago, when booting my laptop it displayed the above error and loaded into the BIOS boot screen (instead of the standard Ubuntu: Choose OS screen). On the BIOS boot screen it shows all of my partitions, but when I choose one (or any, for that matter), it attempts to boot but just ends up at the same screen after a few seconds.
The first time this happened it booted just fine after about 2 or 3 reboots. The second time I noticed that the internal clock was off by precisely 2 hours, and after recalibrating the clock, it booted just fine. The third time, it booted fine after switching from UEFI to legacy boot. The time after that, none of the above attempts worked, so I checked the inside of the laptop to see if everything was still in place (it was), and after I closed up my laptop it worked just fine. The last time this happened the computer worked fine after switching BACK from legacy to UEFI.
(UEFI Bios Version: ROPET47W (1.24) )
In the BIOS setup, I disabled the network boot, and in the boot-section it found all hard-drives + partitions (these were the solution attempts presented on this page).
From what I've found, the two reasons for this error are either: a. not finding a network to boot from, and b. not finding a hard drive to boot from. What confuses me is that, ad. a. I turned off network boot, so this shouldn't be an issue, and ad. b. the BIOS setup finds the hard drives just fine, so it shouldn't be a connector issue.
I also played around with the boot order, but this didn't change anything.
The standard boot order is:
Ubuntu, Windows, nvme0, SanDisk SSD, USB, CD, PXE
Again, there are times when the laptop boots just fine, but (most) times it fusses about like this. Even though it's always been fixable (up till now), it is quite a nuisance, and since there hasn't been a single repeatable solution, I was hoping someone else has encountered this problem / knows where it's possibly coming from.
The exact error that's flashed before going to the BIOS boot screen is:
Realtek PCIe GBE Family Controller Series v2.65 (01/17/17)
PXE-E61: Media test failure, check cable
PXE-M0F: Exiting PXE ROM.
Your laptop manufacturer is exclusively responsible for the BIOS in your laptop; Intel has no role in its development or operation. You need to be talking to Lenovo, not Intel.
I understand that, but directly on the error screen the first thing it mentions it Intel UNDI, PXE-2.1 (build 083), so I figured this had something to do with the built in Intel as well.