UART0(J1 connector) of BeagleboneBlack

We had a weird problem when running our Beaglebone black board with Linux. We boot the system every 5 minutes.

The UART0 (J1 connector) of BBB is tied to the serial console of the system by default, and it prints out a lot of logs via serial cable if the cable is connected. The board runs very well when the UART0 is connected with a serial cable.

If the serial cable is not connected, the board would run around 1-6 hours and after that, it can not boot up again.The more logs that we print out on the serial console, the quicker the board goes down and can not boot up again. Rebooting will also print a lot of boot logs on the console.

Would the buffer on UART0 of BBB side getting full cause the board crashing and not booting up again, since the serial cable is not connected and the UART0 has no outlet?

Is there any ways to disable the boot logs when system boots up? Or is there a way to collect those logs? Thanks. The board version is BBB A6C.