PyQt5 application crashes after some time

I am doing a PyQt 5 application. It works but after approx. 5 minutes it crashes and I don't know why:
Process finished with exit code -1073740791 (0xC0000409)
My idea is that is due to two matplotlib graphs widgets which update every 5 seconds. I think that when new graph appear on the screen old one is still "somewhere" and after these 5 minutes I have over 100 graphs. Sometimes, with crashes the following message appears:

Traceback (most recent call last):
  File "C:\Users\DEN\AppData\Local\Programs\Python\Python37-32\lib\site-packages\matplotlib\backends\backend_qt5.py", line 505, in _draw_idle
    self.draw()
  File "C:\Users\DEN\AppData\Local\Programs\Python\Python37-32\lib\site-packages\matplotlib\backends\backend_agg.py", line 386, in draw
    self.renderer = self.get_renderer(cleared=True)
  File "C:\Users\DEN\AppData\Local\Programs\Python\Python37-32\lib\site-packages\matplotlib\backends\backend_agg.py", line 399, in get_renderer
    self.renderer = RendererAgg(w, h, self.figure.dpi)
  File "C:\Users\DEN\AppData\Local\Programs\Python\Python37-32\lib\site-packages\matplotlib\backends\backend_agg.py", line 86, in __init__
    self._renderer = _RendererAgg(int(width), int(height), dpi)
MemoryError: In RendererAgg: Out of memory

But I'm not sure about that. Could you suggest why it can happen.