Rendering of timelapse failed with return code -11

What is the problem?
When I'm clicking the button to render an unrendered timelapse that has got 907 frames, it does not render telling me this error: "Rendering of timelapse "name of the timelapse" failed with return code -11".
I've search over this forum an internet and haven't found any solution.
imagen
What did you already try to solve it?
I've checked if the photos(frames) are in the folder (they are) , and I've check if /usr/bin/avconv exists as the timelapse section on settings does.

Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, octoprint.log, serial.log or output on terminal tab, ...)
octoprint.log only shows this:

2019-01-03 09:46:50,514 - octoprint.timelapse - WARNING - Could not render movie, got return code -11:
2019-01-03 09:46:51,290 - octoprint.timelapse - WARNING - Could not render movie, got return code -11:
2019-01-03 09:47:39,531 - octoprint.timelapse - WARNING - Could not render movie, got return code -11:
2019-01-03 09:51:59,021 - octoprint.timelapse - WARNING - Could not render movie, got return code -11:
2019-01-03 09:56:01,431 - octoprint.timelapse - WARNING - Could not render movie, got return code -11:

Is there a log specific for the plugin?

Does mjpg_streamer log to /var/log/messages?

UPDATE
I FIXED IT:
I Followed this tutorial:

https://www.jeffreythompson.org/blog/2014/11/13/installing-ffmpeg-for-raspberry-pi/

and reinstalled FFMPEG AGAIN.
Finally, I put the FFMPEG PATH in octoprint to:

/usr/src/FFmpeg/ffmpeg

and working again.
Thanks to the community for answering to fast.