The full warning is WARNING: Invalid URL 'C:/Users/xxxxx/OneDrive/Documents/my_Webots_learning/controllers/autonomous_vehicle/'. Sounds must be in '.mp3' or '.wav' format. WARNING: MyMicro_Car "vehicle(1)" > Speaker "engine_speaker": Impossible to play ''. Make sure the file format is supported (8 or 16 bits, mono or stereo wave).

I have made my own vehicle proto from the Car robot and use the autonomous vehicle controller. Everything works for the most part, I am driving manually until I can learn to program the autonomous behavior, but this warning fills the console repeatedly and no sound is played. I don't think I have altered anything relating to the engine speaker, but I can't figure out where the speaker file is specified. It is not in the Car proto nor the autonomous vehicle controller as far as I can find. I do not needs sounds, just want the warning to stop.

Thanks in advance

  • $\begingroup$ what's an engine speaker? $\endgroup$
    – jsotola
    Jul 12, 2023 at 2:19

1 Answer 1


This warning tells you that no sound file is found for your model.

You should copy the sounds directory from the Webots installation path $WEBOTS_HOME/projects/vehicles/protos/sounds in your project path C:/Users/xxxxx/OneDrive/Documents/my_Webots_learning/worlds/sounds or in the same folder as you vehicle PROTO model.

Note that the Car PROTO has the field engineSound, so to suppress the warning you could also clear it and set it to "". This will disable the speaker and the warning.

Disclaimer: I am a software developer at Webots.


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