I noticed some odd behaviour when running some turtle code I wrote using python 3.5. A simplified example:

>>> from turtle import Turtle
>>> t = Turtle()
>>> t.getscreen().bye() # or manually close the turtle window
>>> t2 = Turtle()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.5/turtle.py", line 3816, in __init__
    visible=visible)
  File "/usr/lib64/python3.5/turtle.py", line 2557, in __init__
    self._update()
  File "/usr/lib64/python3.5/turtle.py", line 2660, in _update
    self._update_data()
  File "/usr/lib64/python3.5/turtle.py", line 2646, in _update_data
    self.screen._incrementudc()
  File "/usr/lib64/python3.5/turtle.py", line 1292, in _incrementudc
    raise Terminator
turtle.Terminator
>>>

This code works under 3.4, opening a new turtle window the second time Turtle() is called. Under 3.5, a blank white window opens.

This seems to be related to https://hg.python.org/cpython/rev/1628484c9408, as the only point that raises Terminator is guarded by a check for `if not TurtleScreen._RUNNING:`

Just as an update, I've been working around this by manually setting TurtleScreen._RUNNING to True before calling Turtle() again, which produces the desired behaviour in both 3.4 and 3.5. Haven't noticed any bad effects so far.

Serhiy, is this a quick fix you can get in?

Thanks for pointing out the workaround.  Was driving me crazy.  Possible fix is to add TurtleScreen._RUNNING = True ~line 967 in turtle.py, in TurtleScreen.__init__ function.

PR has been sent.

Hi all,
Sorry. I seem to have stepped on someone's toes or no one likes turtle any more (as this is active since 2016). As you can see, I am new here and still getting a feel for these procedures. I was preparing a Jupyter notebook for my students. I planned some exercises with turtle at start before we jump into real robots. I noticed this annoying Terminator error, digged deeper into the code to find about the _RUNNING class variable. The PR from Furkan suggest to remove the Raise Terminator. May be we could amend that and I will close my PR, if you prefer. 

Thanks,