OSError: [Errno 28] No space left on device

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "electrum\gui\qt\fee_slider.py", line 26, in on_fee_type
  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 28] No space left on device