fix #4577

electrum/base_wizard.py

@@ -34,7 +34,7 @@ from .keystore import bip44_derivation, purpose48_derivation
 from .wallet import Imported_Wallet, Standard_Wallet, Multisig_Wallet, wallet_types, Wallet
 from .storage import STO_EV_USER_PW, STO_EV_XPUB_PW, get_derivation_used_for_hw_device_encryption
 from .i18n import _
-from .util import UserCancelled, InvalidPassword
+from .util import UserCancelled, InvalidPassword, WalletFileException
 
 # hardware device setup purpose
 HWD_SETUP_NEW_WALLET, HWD_SETUP_DECRYPT_WALLET = range(0, 2)
@@ -106,10 +106,20 @@ class BaseWizard(object):
         self.choice_dialog(title=title, message=message, choices=choices, run_next=self.on_wallet_type)
 
     def upgrade_storage(self):
+        exc = None
         def on_finished():
+            if exc is None:
                 self.wallet = Wallet(self.storage)
                 self.terminate()
-        self.waiting_dialog(partial(self.storage.upgrade), _('Upgrading wallet format...'), on_finished=on_finished)
+            else:
+                raise exc
+        def do_upgrade():
+            nonlocal exc
+            try:
+                self.storage.upgrade()
+            except Exception as e:
+                exc = e
+        self.waiting_dialog(do_upgrade, _('Upgrading wallet format...'), on_finished=on_finished)
 
     def load_2fa(self):
         self.storage.put('wallet_type', '2fa')

electrum/gui/kivy/uix/dialogs/installwizard.py

@@ -957,7 +957,12 @@ class InstallWizard(BaseWizard, Widget):
             # on  completion hide message
             Clock.schedule_once(lambda dt: app.info_bubble.hide(now=True), -1)
             if on_finished:
-                Clock.schedule_once(lambda dt: on_finished(), -1)
+                def protected_on_finished():
+                    try:
+                        on_finished()
+                    except Exception as e:
+                        self.show_error(str(e))
+                Clock.schedule_once(lambda dt: protected_on_finished(), -1)
 
         app = App.get_running_app()
         app.show_info_bubble(

electrum/wallet.py

@@ -1661,4 +1661,4 @@ class Wallet(object):
             return Multisig_Wallet
         if wallet_type in wallet_constructors:
             return wallet_constructors[wallet_type]
-        raise RuntimeError("Unknown wallet type: " + str(wallet_type))
+        raise WalletFileException("Unknown wallet type: " + str(wallet_type))