Unable to open modem DFU socket - mfw v1.0.1

[jbrzozoski]

I received some A/B differential modem firmware for testing the modem FOTA, but am unable to open the DFU socket at all.  I am currently using mfw_nrf9160_1.0.1 and NRFX library from commit a806f5fcac3bde98c4c7324a0c4d547b4ba89f75.

When I try to start the download, the application grabs the first fragment, recognizes it as modem firmware, then gets a result code of -1 when it tries to open the socket.

[00:01:12.580,963] <inf> download_client: Attempting to connect over IPv4
[00:01:12.850,830] <inf> download_client: Connected to www.mycompany.com
[00:01:12.850,830] <inf> download_client: Configuring socket timeout (30 s)
[00:01:12.850,860] <inf> download_client: Downloading: /dfu_9b7e_to_4eea.bin [0]
[00:01:13.049,896] <wrn> download_client: Copying 397 payload bytes
[00:01:13.250,488] <inf> download_client: Downloaded 2048/30590 bytes (6%)
[00:01:13.250,518] <err> dfu_target_modem: Failed to open Modem DFU socket.
[00:01:13.250,549] <err> fota_download: dfu_target_init error -1
[00:01:13.250,579] <inf> download_client: Fragment refused, download stopped.

Is there some pre-requisite I'm missing for this to work?

[jbrzozoski]

I dropped in some extra logging and went to retry the DFU update and .... the socket opened normally?

Download worked just fine!  Our app wasn't ready for the thread calling bsd_init() to hang that long on the next bootup, but that's our fault.

I triggered another reboot after a minute or so and the system came up just fine running the alternate modem firmware...

Not sure why that failed on my first half-dozen attempts but worked just fine this time.

... I'm in a pretty good habit of running west update after every git fetch/pull, but maybe I forgot once?  I dunno.

I'm going to try testing it a bunch more today, and if it doesn't happen again by the end of the day I'm willing to chalk it up to user error.