diff --git a/electrum/gui/qml/qedaemon.py b/electrum/gui/qml/qedaemon.py
index 311eebc18..48d36bdd5 100644
--- a/electrum/gui/qml/qedaemon.py
+++ b/electrum/gui/qml/qedaemon.py
@@ -231,7 +231,7 @@ class QEDaemon(AuthMixin, QObject):
                     return
 
                 if self.daemon.config.WALLET_SHOULD_USE_SINGLE_PASSWORD:
-                    self._use_single_password = self.daemon.update_password_for_directory(old_password=local_password, new_password=local_password)
+                    self._use_single_password = self._update_password_for_directory_and_unlock_wallets(old_password=local_password, new_password=local_password)
                     if not self._use_single_password and self.daemon.config.WALLET_ANDROID_USE_BIOMETRIC_AUTHENTICATION:
                         # we need to disable biometric auth if the user creates wallets with different passwords as
                         # we only store one encrypted password which is not associated to a specific wallet
@@ -399,11 +399,24 @@ class QEDaemon(AuthMixin, QObject):
     def setPassword(self, password):
         assert self._use_single_password
         assert password
-        if not self.daemon.update_password_for_directory(old_password=self._password, new_password=password):
+        if not self._update_password_for_directory_and_unlock_wallets(old_password=self._password, new_password=password):
             return False
         self._password = password
         return True
 
+    def _update_password_for_directory_and_unlock_wallets(self, *, old_password, new_password):
+        # note: this assumes all wallet files are in a single directory.
+        # change wallet passwords:
+        ret = self.daemon.update_password_for_directory(old_password=old_password, new_password=new_password)
+        # If some wallets just had their password changed, they got "locked" by wallet.update_password().
+        # If the password is not unified yet, other loaded wallets might still be unlocked.
+        # restore the invariant that all loaded wallets in qml must be unlocked:
+        for w in self.daemon.get_wallets().values():
+            if not w.is_unlocked():
+                w.unlock(new_password)
+            assert w.is_unlocked()
+        return ret
+
     @pyqtProperty(QENewWalletWizard, notify=newWalletWizardChanged)
     def newWalletWizard(self):
         if not self._new_wallet_wizard:
diff --git a/electrum/gui/qml/qewallet.py b/electrum/gui/qml/qewallet.py
index f08005baf..b2b3a64a3 100644
--- a/electrum/gui/qml/qewallet.py
+++ b/electrum/gui/qml/qewallet.py
@@ -765,6 +765,7 @@ class QEWallet(AuthMixin, QObject, QtEventListener):
         try:
             self._logger.info('setting new password')
             self.wallet.update_password(current_password, password, encrypt_storage=True)
+            # restore the invariant that all loaded wallets in qml must be unlocked:
             self.wallet.unlock(password)
             return True
         except InvalidPassword as e:
diff --git a/electrum/wallet.py b/electrum/wallet.py
index cf7874ff0..c852603af 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -3532,16 +3532,27 @@ class Abstract_Wallet(ABC, Logger, EventListener):
         """Returns the number of new addresses we generated."""
         return 0
 
-    def unlock(self, password):
+    def unlock(self, password: Optional[str]) -> None:
         self.logger.info(f'unlocking wallet')
+        password = password or None
         self.check_password(password)
         self._password_in_memory = password
 
     def lock_wallet(self):
         self._password_in_memory = None
 
-    def get_unlocked_password(self):
-        return self._password_in_memory
+    def get_unlocked_password(self) -> Optional[str]:
+        pw = self._password_in_memory
+        if not self.is_unlocked():
+            return None
+        try:
+            self.check_password(pw)
+        except InvalidPassword as e:
+            raise Exception("inconsistent _password_in_memory") from e
+        return pw
+
+    def is_unlocked(self) -> bool:
+        return self._password_in_memory is not None or not self.has_password()
 
     def get_text_not_enough_funds_mentioning_frozen(
             self,