I'm checked out at today's current head for fw-nrfconnect-nrf ((ecc4ded86716fcf4b94e80efca450b3ddb4b7a26)) and have run "west update" to sync all repos. My modem is loaded with firmware mfw-m1-mb_nrf9160_0.6.8-30.alpha.
I'm building/testing an almost unmodified nrf/samples/nrf9160/http_application_update. My only modifications were adding a printk at the top of main and tweaking the DOWNLOAD_HOST and DOWNLOAD_FILE to point to my own server, which I expect have no affect on the issue I'm seeing.
Everything starts as expected, but 5 different attempts to download have all failed partway. Looking over the serial logs, there is always a "bsdlib recoverable error: 3" error just before things go wrong. In three cases the serial output stopped as though the system hung, and in two cases the serial port infinitely repeated a message like "<inf> http_dfu: Received response of size 424" until I rebooted it.
The download did make progress in each case, but always failed before it got to the end. In each case I forced a reboot and MCUboot continued to boot slot 0, since slot 1 was understandably invalid.
Is this a known issue?