Posts: 24
Joined: Fri Sep 14, 2018 11:22 pm

gpiozero button issue with error "Failed to add edge detection"

Wed Nov 07, 2018 12:18 am

Hi all,
I had started (finally) to getting deeper to gpiozero library so I started to test different scenarios and do things in different ways when I encountered a problem with instances of "Button" object!
the first time I assign a pin to a button it works. second time (sometimes maybe third time, I am not fully aware of this) it doesn't work showing the below traceback and the last error says RuntimeError: Failed to add edge detection

The strange thing is that when I change the button pin it works, then the issue happens again with the new pin! strange! it looks to me like I should gracefully close the button after using it! I tried to add an exception of a keyboard interrupt to close the button and now the button lasted longer when I am working, but it eventually triggered the same error.

I am using RPi 3B with python3. I used Thonny - primarily- when I faced the issue. but when It happens it shows same thing on IDLE as well.

Below is the exact lines that appeared on my screen. any assistance is appreciated.

p.s: i googled and found couple of threads about root permissions issues! my research found that this is a different issue and it is related only to button class!

Code: Select all

Traceback (most recent call last):
  File "", line 11, in <module>
  File "/home/pi/.local/lib/python3.5/site-packages/gpiozero/", line 95, in __call__
    self = super(GPIOMeta, cls).__call__(*args, **kwargs)
  File "/home/pi/.local/lib/python3.5/site-packages/gpiozero/", line 303, in __init__
    pin, pull_up, bounce_time, pin_factory=pin_factory
  File "/home/pi/.local/lib/python3.5/site-packages/gpiozero/", line 338, in __init__
    super(HoldMixin, self).__init__(*args, **kwargs)
  File "/home/pi/.local/lib/python3.5/site-packages/gpiozero/", line 100, in __init__ = self._fire_events
  File "/home/pi/.local/lib/python3.5/site-packages/gpiozero/pins/", line 388, in <lambda>
    lambda self, value: self._set_when_changed(value),
  File "/home/pi/.local/lib/python3.5/site-packages/gpiozero/pins/", line 289, in _set_when_changed
  File "/home/pi/.local/lib/python3.5/site-packages/gpiozero/pins/", line 219, in _enable_event_detect
RuntimeError: Failed to add edge detection

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Re: gpiozero button issue with error "Failed to add edge detection"

Wed Nov 07, 2018 7:11 am

I think I've fixed it. Read more here:

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