Build error when merging projects

I am doing rapid development for a project, using the nRF52840 DK. Two key features are USB and BLE central role.

I started with the usb_cdc_acm project and am merging in ble_app_blinky_c.

I added the following information from ble_app_blinky_c:

  1. Component files
  2. sdk_config.h entries
  3. preprocessor include folders
  4. preprocessor defines

I get build errors. It is complaining that NRF_SUCCESS is undefined, and I determined that there is more than one file named nrf_error.h and they are different!

Do I need to change the directory order in the preprocessor include folder list?

Is there something else I am missing?