Traceback (most recent call last):
  File "electrum/gui/qt/network_dialog.py", line 410, in set_server
  File "electrum/network.py", line 385, in run_from_another_thread
  File "concurrent/futures/_base.py", line 446, in result
  File "concurrent/futures/_base.py", line 391, in __get_result
  File "electrum/util.py", line 1310, in wrapper
  File "electrum/network.py", line 656, in set_parameters
  File "electrum/network.py", line 676, in switch_lagging_interface
  File "electrum/blockchain.py", line 482, in header_at_tip
  File "electrum/util.py", line 1339, in func_wrapper
  File "electrum/blockchain.py", line 469, in read_header
  File "electrum/blockchain.py", line 433, in assert_headers_file_available
FileNotFoundError: Cannot find headers file but headers_dir is there. Should be at /Users/imac/.electrum/blockchain_headers