On this snap (could have been earlier as well) I received a...
...error on usb 3-4 at boot up with lots of usb 3-4: device descriptor read/64 and device not accepting address XX messages .
So I ...
and did ...
In my case this displayed two files with 0000:00:XX.X names.
I entered the command...
echo -n "0000:00:XX.X" > unbind
for both files and this slowed the messages down quite a bit. At least it made it easier to enter command prompt entries without having everything overwritten by the terminal output messages.
This had to be re-entered every time I rebooted.
So I put the commands into /etc/rc.local and rebooted.
echo -n "0000:00:XX.X" > unbind /sys/bus/pci/drivers/ehci_hcd
They don't come up as nearly often but they still annoy during troubleshooting.
I don't understand why they still pop up - period, but it's way less annoying than before.