Solved by using make for building the application.

So, using make instead of idf.py it works.

Thanks to all!

Best regards,
Francisco

Hi, all

Using ESP-IDF release/v4.1 and ESP-ADF v2.1 , I'm unable to build the "duerOS" example, the error messages complain about missing symbols during the link phase:

The last messages are as following:
[1042/1043] Linking CXX executable esp_dueros.elf
FAILED: esp_dueros.elf
: && /home/frares ...