Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/send_tab.py", line 573, in do_pay_or_get_invoice
    self.do_pay_invoice(self.pending_invoice)
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/send_tab.py", line 585, in do_pay_invoice
    self.pay_onchain_dialog(self.window.get_coins(), invoice.outputs)
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/send_tab.py", line 260, in pay_onchain_dialog
    self.save_pending_invoice()
  File "/usr/lib/python3/dist-packages/electrum/gui/qt/send_tab.py", line 529, in save_pending_invoice
    self.wallet.save_invoice(self.pending_invoice)
  File "/usr/lib/python3/dist-packages/electrum/wallet.py", line 1001, in save_invoice
    self.save_db()
  File "/usr/lib/python3/dist-packages/electrum/wallet.py", line 390, in save_db
    self.db.write(self.storage)
  File "/usr/lib/python3/dist-packages/electrum/wallet_db.py", line 1516, in write
    self._write(storage)
  File "/usr/lib/python3/dist-packages/electrum/util.py", line 446, in <lambda>
    return lambda *args, **kw_args: do_profile(args, kw_args)
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/electrum/util.py", line 442, in do_profile
    o = func(*args, **kw_args)
        ^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/electrum/wallet_db.py", line 1526, in _write
    storage.write(json_str)
  File "/usr/lib/python3/dist-packages/electrum/storage.py", line 84, in write
    with open(temp_path, "w", encoding='utf-8') as f:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: [Errno 30] Read-only file system: '/home/user/.electrum/wallets/default_wallet.tmp.2242'