How to debug when program flow goes to 0xFFFFFFFE?

[nordicdev]

Hi, when doing wired uart-BLE combination and increasing the traffic in the uart comms and BLE comms, at some unpredictable stage, the program flow goes to 0xFFFFFFFE. Any thoughts as how to debug this? I do APP_ERROR_CHECK every time and it is fine. Also I have breakpoint in NVIC_SystemReset and it is never hit. I am using SDK12.0.1 keil IDE and sd130v2 on nRF51822 32KBRAM version.

[Nguyen Hoan Hoang]

Looks like bad pointer or lockup some where. Traffic increase means using more buffers and you ran out of buffers. So you likely to lockup and softdevice doesn't like it and goes to hardfault.