diff --git a/cura/CuraApplication.py b/cura/CuraApplication.py
index 474d47fbaa..d24ce28da5 100755
--- a/cura/CuraApplication.py
+++ b/cura/CuraApplication.py
@@ -217,7 +217,7 @@ class CuraApplication(QtApplication):
 
         self._quality_profile_drop_down_menu_model = None
         self._custom_quality_profile_drop_down_menu_model = None
-        self._cura_API = CuraAPI(self)
+        self._cura_API = None
 
         self._physics = None
         self._volume = None
@@ -682,8 +682,8 @@ class CuraApplication(QtApplication):
     def messageBox(self, title, text,
                    informativeText = "",
                    detailedText = "",
-                   buttons = QMessageBox.Ok,
-                   icon = QMessageBox.NoIcon,
+                   buttons = QMessageBox.StandardButton.Ok,
+                   icon = QMessageBox.Icon.NoIcon,
                    callback = None,
                    callback_arguments = []
                    ):
@@ -837,7 +837,7 @@ class CuraApplication(QtApplication):
         self._setting_visibility_presets_model = SettingVisibilityPresetsModel(self.getPreferences(), parent = self)
 
         # Initialize Cura API
-        self._cura_API.initialize()
+        self._cura_API = self.getCuraAPI()
         self.processEvents()
         self._output_device_manager.start()
         self._welcome_pages_model.initialize()
@@ -1087,7 +1087,7 @@ class CuraApplication(QtApplication):
     def event(self, event):
         """Handle Qt events"""
 
-        if event.type() == QEvent.FileOpen:
+        if event.type() == QEvent.Type.FileOpen:
             if self._plugins_loaded:
                 self._openFile(event.file())
             else:
@@ -1114,6 +1114,9 @@ class CuraApplication(QtApplication):
         return self._custom_quality_profile_drop_down_menu_model
 
     def getCuraAPI(self, *args, **kwargs) -> "CuraAPI":
+        if not self._cura_API:
+            self._cura_API = CuraAPI(self)
+            self._cura_API.initialize()
         return self._cura_API
 
     def registerObjects(self, engine):
diff --git a/cura/Settings/MachineNameValidator.py b/cura/Settings/MachineNameValidator.py
index 7fc1789f13..409365ef97 100644
--- a/cura/Settings/MachineNameValidator.py
+++ b/cura/Settings/MachineNameValidator.py
@@ -1,7 +1,7 @@
 # Copyright (c) 2021 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
-from PyQt6.QtCore import pyqtSlot, pyqtProperty, QObject, pyqtSignal, QRegExp
+from PyQt6.QtCore import pyqtSlot, pyqtProperty, QObject, pyqtSignal
 from PyQt6.QtGui import QValidator
 import os #For statvfs.
 import urllib #To escape machine names for how they're saved to file.
@@ -65,6 +65,6 @@ class MachineNameValidator(QObject):
             self.validation_regex = "a^" #Never matches (unless you manage to get "a" before the start of the string... good luck).
         self.validationChanged.emit()
 
-    @pyqtProperty("QRegExp", notify=validationChanged)
+    @pyqtProperty(str, notify=validationChanged)
     def machineNameRegex(self):
-        return QRegExp(self.machine_name_regex)
\ No newline at end of file
+        return str(self.machine_name_regex)
\ No newline at end of file
diff --git a/cura_app.py b/cura_app.py
index 001e71775e..4b689fdadb 100755
--- a/cura_app.py
+++ b/cura_app.py
@@ -156,7 +156,7 @@ def exceptHook(hook_type, value, traceback):
     # If the application has finished its initialization and was running fine, and then something causes a crash,
     # we run the old routine to show the Crash Dialog.
     #
-    from PyQt6.Qt import QApplication
+    from PyQt6.QtWidgets import QApplication
     if CuraApplication.Created:
         _crash_handler = CrashHandler(hook_type, value, traceback, has_started)
         if CuraApplication.splash is not None:
@@ -228,7 +228,7 @@ if Platform.isLinux():
     
 if ApplicationMetadata.CuraDebugMode:
     ssl_conf = QSslConfiguration.defaultConfiguration()
-    ssl_conf.setPeerVerifyMode(QSslSocket.VerifyNone)
+    ssl_conf.setPeerVerifyMode(QSslSocket.PeerVerifyMode.VerifyNone)
     QSslConfiguration.setDefaultConfiguration(ssl_conf)
 
 app = CuraApplication()