File "/usr/lib/python3/dist-packages/electrum/gui/qt/invoice_list.py", line 166, in <lambda>
    menu.addAction(_("Pay"), lambda: self.parent.do_pay_invoice(invoice))
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/main_window.py", line 1588, in do_pay_invoice
    self.pay_onchain_dialog(self.get_coins(), invoice.outputs)
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/main_window.py", line 1624, in pay_onchain_dialog
    d = ConfirmTxDialog(window=self, make_tx=make_tx, output_value=output_value, is_sweep=is_sweep)
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/confirm_tx_dialog.py", line 175, in __init__
    BlockingWaitingDialog(window, _("Preparing transaction..."), self.update_tx)
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/util.py", line 335, in __init__
    task()
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/confirm_tx_dialog.py", line 86, in update_tx
    self.tx = self.make_tx(fee_estimator)
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/main_window.py", line 1617, in <lambda>
    is_sweep=is_sweep)
  File "/usr/lib/python3/dist-packages/electrum/wallet.py", line 1211, in make_unsigned_transaction
    tx.locktime = get_locktime_for_new_transaction(self.network)
  File "/usr/lib/python3/dist-packages/electrum/wallet.py", line 199, in get_locktime_for_new_transaction
    if chain.is_tip_stale():
  File "/usr/lib/python3/dist-packages/electrum/blockchain.py", line 490, in is_tip_stale
    header = self.header_at_tip()
  File "/usr/lib/python3/dist-packages/electrum/blockchain.py", line 486, in header_at_tip
    return self.read_header(height)
  File "/usr/lib/python3/dist-packages/electrum/blockchain.py", line 201, in func_wrapper
    return func(self, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/electrum/blockchain.py", line 478, in read_header
    raise Exception('Expected to read a full header. This was only {} bytes'.format(len(h)))