Traceback (most recent call last):
  File "app/electrum/bitcoin.py", line 575, in base_decode
KeyError: 73

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "app/electrum/gui/qml/qewallet.py", line 852, in signMessage
  File "app/electrum/wallet.py", line 3193, in sign_message
  File "app/electrum/keystore.py", line 226, in sign_message
  File "app/electrum/keystore.py", line 710, in get_private_key
  File "app/electrum/bip32.py", line 137, in from_xkey
  File "app/electrum/bitcoin.py", line 592, in DecodeBase58Check
  File "app/electrum/bitcoin.py", line 577, in base_decode
electrum.bitcoin.BaseDecodeError: Forbidden character 73 for base 58