nRF9151 modem lock up, can't reprogram

RE: nRF9151 modem lock up, can't reprogram

Carl Richard — Thu, 19 Mar 2026 13:15:56 GMT

Hi again!

Have you had any progress on your issue? I've had a discussion with the developers on this and it was mentioned that this behaviour can be related to a HW-issue. Specifically a faulty clock source (TCXO for example). Could this be the case for you?

Best regards,
Carl Richard

RE: nRF9151 modem lock up, can't reprogram

Carl Richard — Fri, 27 Feb 2026 14:08:34 GMT

Thanks.

I've tried to reproduce the issue here using the https_client sample, without success. A couple of things you can try while we wait for a response from the developers:

Recovering the DK as described here to ensure that it's not an issue with the application processor.
After this, try to test the AT Client sample to see if you can communicate with the modem at all. You can also try programming the MFW again.

Also: are you using a custom board or a nRF9151 DK? In the latter case, which version?

Best regards,
Carl Richard

RE: nRF9151 modem lock up, can't reprogram

Redrield — Thu, 26 Feb 2026 14:23:20 GMT

Our firmware is a lot more expansive that the part that triggered the bug, so I'll summarize it here.

1. init modem library, connect to lte. We do this in the same way as samples, lte_lc_connect_async with a semaphore given in the callback when the device is connected
2. Set up socket to connect over TLS to some server. Target shouldn't matter
3. Before the calls to `socket` and `connect`, I added the following

struct tm tm = { .tm_sec = 0, .tm_min = 0, .tm_hour = 0, .tm_mon = 0, .tm_mday = 1, .tm_year = 115, }; // Defined above the function call, timestamp of 2015-01-01T00:00:00Z date_time_set(&tm); sock = socket(...); ... date_time_set(&tm); connect(sock, ...);

With kconfig definitions CONFIG_DATE_TIME=y, CONFIG_DATE_TIME_MODEM=y (To ensure the timestamp update is sent to the modem)

The 2 calls to date_time_set completed successfully, and the modem panic occurred almost immediately after.

RE: nRF9151 modem lock up, can't reprogram

Carl Richard — Thu, 26 Feb 2026 12:45:31 GMT

Hi again!

Thanks. Could you also share the program that triggered this issue? I want to try to reproduce it.

We can make the ticket private if you don't want to share this publicly.

Best regards,
Carl Richard

RE: nRF9151 modem lock up, can't reprogram

Redrield — Wed, 25 Feb 2026 14:24:38 GMT

Hi Carl,

I tried to program the modem with `nrfutil device program --firmware mfw_nrf91x1_2.0.4.zip`

RE: nRF9151 modem lock up, can't reprogram

Carl Richard — Wed, 25 Feb 2026 12:53:45 GMT

Hi Redrield!

Thanks for reaching out. The modem should not behave like this. I've reached out to the developers to see if they can provide som insight.

Could you share the exact nrfutil-command you used to program the modem firmware?

Best regards,
Carl Richard