[SOLVED] DFU: Failed to reopen transport backend

[Nate]

There have been a number of other older topics with this same error message symptom, but I've tried all the solutions proposed and none have worked to solve this specific problem for me so far. I'm simply following the official DFU Tutorial using "Option A: Packs structure" with Master Control Panel and the DFU fails. After it fails, the nRF51-DK becomes unresponsive and must be flashed via USB again before it can be connected to or discovered again.

• OS: Windows 10 MCP ver 3.10.0.14
• Project: ble_app_hrs_s110_with_dfu_pca10028 (Keil Pack)
• Update File: "dfu_test_app_hrm.zip"
• Master Control Panel Log File

Additionally, the iOS nRF Toolbox app does not enable the button to perform the update after selecting all necessary items so I haven't been able to attempt DFU over iOS.

Is anyone able to follow the same steps in the tutorial with success? I'm hoping it's simply a configuration issue with Keil and not a deeper problem. Thanks!

[Vidar Berg]

Hi, did you remember to program the bootloader first? This is a separate program loaded above the application (memory layout). The application will "jump" to the bootlaoder application when you send the "DFU start" command.

[Vidar Berg]

Happy to help:) the newer releases of nrfjprog (program used to program the bootloader) does not support multiple command arguments which is why --program and --reset didn't work. The reset argument was thus removed in SDK 9.0.0. To make the program run after programming you can manually press the reset pin on the kit, or call nrfjprog --reset in a separately after programming.

Also, recommend to use the bootloader form SDK 8 or later due to the issue mentioned here.