Unable to establish BLE connection after porting SDK version from 11.0.0 to 12.1.0

[RahulR]

I carried out following steps:

1. Application was using SDK 11.0.0 for nRF51 SoC
2. Ported SDK version 12.1.0
3. Using secure DFU boot-loader from SDK 12.1.0 (followed all steps mentioned under blog https://devzone.nordicsemi.com/nordic/short-range-guides/b/software-development-kit/posts/getting-started-with-nordics-secure-dfu-bootloader)
4. Erased flash and updated with secure boot-loader + soft device s130_nrf51_2.0.1
5. Generated signed DFU .zip package with --sd-req set to 0x87 and with the private key
6. Able to flash signed DFU package successfully through nrfConnect App
7. Device BLE scan/broadcast data has correct name of device as defined.
8. Power reset the device to confirm that the application is running as expected.
9. On sending BLE command/attempting to DFU, unable to establish BLE connection.
10. Below error is reported on nrfConnect while attempting to perform DFU operation.

                 

Need support in addressing this issue.

Thanks,

Rahul

[RahulR]

Below are the values for DFU characteristics defined in the application code.

#define BLE_DFU_SERVICE_UUID           0x1530   /**< The UUID of the DFU Service. */
#define BLE_DFU_PKT_CHAR_UUID       0x1532   /**< The UUID of the DFU Packet Characteristic. */
#define BLE_DFU_CTRL_PT_UUID          0x1531   /**< The UUID of the DFU Control Point. */
#define BLE_DFU_STATUS_REP_UUID   0x1533   /**< The UUID of the DFU Status Report Characteristic. */
#define BLE_DFU_REV_CHAR_UUID       0x1534   /**< The UUID of the DFU Revision Characteristic. */