I am running the Dev Academy Lesson 4 Exercise 2 - MQTT with TLS and getting the error:
[00:00:00.650,085] <err> nrf_modem: Modem has crashed, reason 0x4, PC: 0xecb64
I see that is a modem firmware memory management fault. The first time I built and flashed the program, it worked fine. When I reset the system, I started seeing the error. I've erased the flash, done "west flash --recovery", and cycled power. All give the same result.
A bit of debugging shows the error gest triggered from within the call to modem_key_mgmt_cmp(). Specifically, the call to key_fetch(sec_tag, cred_type) returns -110; I suspect this underlying cause. If I comment out the code that calls modem_key_mgmt_exists() and modem_key_mgmt_cmp(), thus always writing the certificate to the modem, the application works fine.
I'm using a nRF9160 DK and SDK v2.6.1.
Thanks,
Rick