Traceback (most recent call last):
  File "electrum\bitcoin.py", line 591, in base_decode
KeyError: 73

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "electrum\util.py", line 1081, in run_with_except_hook
  File "threading.py", line 953, in run
  File "electrum\gui\qt\main_window.py", line 2279, in privkeys_thread
  File "electrum\wallet.py", line 815, in export_private_key
  File "electrum\keystore.py", line 699, in get_private_key
  File "electrum\bip32.py", line 136, in from_xkey
  File "electrum\bitcoin.py", line 608, in DecodeBase58Check
  File "electrum\bitcoin.py", line 593, in base_decode
electrum.bitcoin.BaseDecodeError: Forbidden character 73 for base 58