File "electrum\gui\qt\network_dialog.py", line 105, in <lambda>
  File "electrum\gui\qt\network_dialog.py", line 379, in follow_server
  File "electrum\network.py", line 369, in run_from_another_thread
  File "concurrent\futures\_base.py", line 435, in result
  File "concurrent\futures\_base.py", line 384, in __get_result
  File "electrum\network.py", line 1094, in follow_chain_given_server
  File "electrum\network.py", line 1072, in _set_preferred_chain
  File "electrum\simple_config.py", line 160, in set_key
  File "electrum\simple_config.py", line 169, in _set_key_in_user_config
  File "electrum\simple_config.py", line 262, in save_user_config