SDK17.1, SD140, nRF52840, sd_ble_gap_phy_update() sometimes errors with 0x08 (INVALID_STATE)

Hello,

We have a product using an nRF52840, with the SDK17.1, the 140 Softdevice, and an application based around the Nordic UART service (nus). We are seeing application crashes caused by the following code:

static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    uint32_t err_code;

    switch (p_ble_evt->header.evt_id)
    {
        /* Other, not relevant cases */
        
        case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
        {
            NRF_LOG_INFO("PHY update request.");
            ble_gap_phys_t const phys =
            {
                .rx_phys = BLE_GAP_PHY_AUTO,
                .tx_phys = BLE_GAP_PHY_AUTO,
            };
            err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
            APP_ERROR_CHECK(err_code);
        } break;
        
        default:
            // No implementation needed.
            break;
    }
}

The returned error code is 0x08 (INVALID_STATE)

We think this is likely to be similar to our previous issue: https://devzone.nordicsemi.com/f/nordic-q-a/86152/sdk-15-2-0-sd-132-nrf52832-qfaa-sd_ble_gap_data_length_update-sometimes-errors-with-0x08-invalid_state and are planning to just ignore INVALID_STATE errors here in the future.

Still, can you explain what might cause these and confirm that they are safe to ignore?

Like in the previous case we aren't able to reproduce these reliably.

Thanks,
Mark