Custom TWIS DFU transport in SDK15 on S132v6: Flash erase error 3 on Init Packet executehttps://devzone.nordicsemi.com/f/nordic-q-a/32991/custom-twis-dfu-transport-in-sdk15-on-s132v6-flash-erase-error-3-on-init-packet-executeHello! SDK15&#39;s DFU with app_scheduler is great! I am able to Select, Create, and Write an Init Packet. On Execute, however, I get &quot;Flash erase failed (0x3)&quot;. What might I be doing wrong? In the log below, &#39;wr&#39; happens in NRFX_TWIS_EVT_WRITE_REQen-USTelligent Community 13Tue, 03 Apr 2018 19:56:33 GMTRE: Custom TWIS DFU transport in SDK15 on S132v6: Flash erase error 3 on Init Packet executehttps://devzone.nordicsemi.com/thread/126716?ContentTypeID=1Tue, 03 Apr 2018 19:56:33 GMT137ad170-7792-4731-bb38-c0d22fbe4515:0c3dfca6-56ea-42cf-963a-e10097dd6d24lesher<p>I added nrf_dfu_ble.c back into the build (two transports exist) and now flash erase/write works. My issue could be related to something in there making the system understand that is needs to use sd instead of nvmc to handle flash. I want both transports present, so I&#39;m going to mark this as the answer - though any additional information is welcome.</p><div style="clear:both;"></div>RE: Custom TWIS DFU transport in SDK15 on S132v6: Flash erase error 3 on Init Packet executehttps://devzone.nordicsemi.com/thread/126557?ContentTypeID=1Tue, 03 Apr 2018 02:33:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6232aa5d-b37c-4167-980e-549d00f1acbclesher<p>The app that will be bootloaded uses the softdevice, but the bootloader does not start the SD. I&#39;m now trying to understand the places where SD_PRESENT and (perhaps)&nbsp;BLE_STACK_SUPPORT_REQD and MBR_SIZE determine sizes and addresses for protection.</p> <p>Note that I copied the secure_bootloader_ble example and added the TWIS transport, then removed nrf_dfu_ble.c from the build so there is enough flash to enable logging.</p><div style="clear:both;"></div>