General thumb rule regarding GRUB errors and warnings:
If you don’t have an actual issue, ignore the messages. Kernel messages almost always output some weird log messages, sometimes warnings and errors. However, most of the time they are not important.
Start caring, if you are actually affected by an issue.
I mean… I’m a bit less eager than @Akito to just ignore that message. It means something. Specifically, the kernel appears to be detecting a USB-attached device that’s failing to configure.
That device doesn’t have to be a PORT, per se. Many systems use USB for internal connections as well, these days. Things like card readers (especially), wireless devices, IR receivers, etc, etc. can all have internal connections to the USB bus.
It’s possible there isn’t any device attached there, and the detection is just a “phantom” port that was left unconnected rather than disconnected. Maybe it’s not properly grounded or something. Or it could be that there’s a built-in device which isn’t supported under Linux, maybe never was, so it’s not ever going to be working. (I had one system that always detected a USB-attached IR receiver, I never did figure out if it was actually there and not working, or just a phantom device.)
Two things you could try, if you wanted to investigate further:
Run dmesg -T |grep -i usb shortly after booting the system, and see if any of the kernel messages give more of an idea of what device it thinks it’s detecting. The -T turns on clock-time timestamps.
(You could use sudo journalctl -b --grep usb instead, to search the entire journal since the system booted up, but that’ll be a lot more cluttered and isn’t likely to provide that much additional info, you’ll just have to slog through more noise.)
Run lsusb -t and see if you can get an idea of what “usb 1-6” would be connected to. (I believe that’s Bus 01.Port 6 in lsusb parlance, but honestly how the various numberings map has always been something of a mystery to me.)
Alternatively, you could poke around in the /sys/bus/usb/devices/ hierarchy for the same information. But if a USB device isn’t configured, AFAIK it will not show up there. You’re just looking for clues based on adjacent, actually-configured devices.
And then, if you haven’t found any useful info, I’m in full agreement: Ignore it and don’t waste any more time on it. But that “Couldn’t get size” message immediately before… that sounds to me like it could be a failure to install device firmware, which means there may well be a device installed in the system that you don’t know about, and which possibly could be made to work with the right drivers/firmware!
I meant it more like don’t worry. If you want to use up personal time for finding out, why these messages appear, go ahead. However, my point is, that no one should feel obligated to fix something that is not really broken. If you are genuinely interested in investigating how the kernel actually works, knock yourself out.
Thanks for the pointers, FeRDNYC. I appreciate your and Akito’s comments!