OSError: [Errno 9] Bad file descriptor

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "electrum\gui\qt\network_dialog.py", line 425, in set_proxy
  File "electrum\network.py", line 387, in run_from_another_thread
  File "concurrent\futures\_base.py", line 439, in result
  File "concurrent\futures\_base.py", line 388, in __get_result
  File "electrum\util.py", line 1118, in wrapper
  File "electrum\network.py", line 617, in set_parameters
  File "electrum\simple_config.py", line 162, in set_key
  File "electrum\simple_config.py", line 171, in _set_key_in_user_config
  File "electrum\simple_config.py", line 264, in save_user_config
OSError: [Errno 9] Bad file descriptor