Good morning.
I upgrade a 3400 from 20.1R1-S1 to 20.4 20.4R2-S1.6 this morning and I seen a lot of tty error logs after the reboot(136 lines in 50 minutes) .
This could have been a fluke but in case its not and is a odd artifact as root do a kill -HUP 1 and that seemed to have addressed the issue.
Jul 27 07:25:58 switch getty[17550]: %AUTH-3: login_tty /dev/ttyu1: Inappropriate ioctl for device
Jul 27 07:25:58 switch init: %AUTH-1: getty repeating too quickly on port /dev/ttyu1, sleeping 30 secs
at the shell as root
switch:RE:0% kill -HUP 1
PS
I do have my auxiliary com port
auxiliary {
log-out-on-disconnect;
port-type mini-usb;
}