diff --git a/BUILDING.md b/BUILDING.md
index 3fb8b8b..76ec7f5 100644
--- a/BUILDING.md
+++ b/BUILDING.md
@@ -7,6 +7,16 @@ $ pip install -r requirements.txt
 $ pip install pyinstaller
 ```
 
+**Alternative: System packages (Debian/Ubuntu)**
+
+If you prefer to use system packages instead of pip, install the required PyQt6 packages:
+
+```shell
+$ apt install python3-pyqt6 python3-pyqt6.qtwebsockets python3-pyqt6.qtmultimedia
+```
+
+Note: This may require specific Python versions and may not include the latest features.
+
 Currently it's only possible to create installer packages from the pyinstaller output. For any target platform, first create the executable with pyinstaller:
 
 ```shell
diff --git a/gotify-tray.spec b/gotify-tray.spec
index 396da10..4dd2fbc 100644
--- a/gotify-tray.spec
+++ b/gotify-tray.spec
@@ -8,7 +8,7 @@ logo = "gotify_tray/gui/images/logo.ico" if platform.system() != "Darwin" else "
 
 a = Analysis(['gotify_tray/__main__.py'],
              pathex=[os.getcwd()],
-             binaries=[('/lib/x86_64-linux-gnu/libpython3.10.so', '.'), ('/lib/x86_64-linux-gnu/libpython3.10.so.1', '.')],
+              binaries=[('/lib/x86_64-linux-gnu/libpython3.12.so', '.'), ('/lib/x86_64-linux-gnu/libpython3.12.so.1', '.')],
              datas=[('gotify_tray/gui/images', 'gotify_tray/gui/images'), ('gotify_tray/gui/themes', 'gotify_tray/gui/themes')],
              hiddenimports=[],
              hookspath=[],
diff --git a/gotify_tray/__main__.py b/gotify_tray/__main__.py
index a5023f5..5aa3175 100644
--- a/gotify_tray/__main__.py
+++ b/gotify_tray/__main__.py
@@ -1,11 +1,21 @@
 def main():
+    import os
     import sys
 
     if "--version" in sys.argv:
         from gotify_tray.__version__ import __version__
+
         print(__version__)
     else:
+        # Check for display before importing GUI modules
+        if not os.environ.get("DISPLAY"):
+            print(
+                "Error: No display environment detected. This application requires a graphical desktop environment to run.",
+                file=sys.stderr,
+            )
+            sys.exit(1)
         from gotify_tray.gui import start_gui
+
         start_gui()
 
 
diff --git a/gotify_tray/gui/MainApplication.py b/gotify_tray/gui/MainApplication.py
index 917ddb8..4bb38ab 100644
--- a/gotify_tray/gui/MainApplication.py
+++ b/gotify_tray/gui/MainApplication.py
@@ -459,9 +459,10 @@ class MainApplication(QtWidgets.QApplication):
         self.main_window.hidden.connect(self.main_window_hidden_callback)
         self.main_window.activated.connect(self.tray.revert_icon)
 
-        self.styleHints().colorSchemeChanged.connect(
-            self.theme_change_requested_callback
-        )
+        if hasattr(self.styleHints(), "colorSchemeChanged"):
+            self.styleHints().colorSchemeChanged.connect(
+                self.theme_change_requested_callback
+            )
 
         self.messages_model.rowsInserted.connect(
             self.main_window.display_message_widgets
diff --git a/gotify_tray/gui/designs/widget_main.py b/gotify_tray/gui/designs/widget_main.py
index 4883949..a51b823 100644
--- a/gotify_tray/gui/designs/widget_main.py
+++ b/gotify_tray/gui/designs/widget_main.py
@@ -1,6 +1,6 @@
 # Form implementation generated from reading ui file 'gotify_tray/gui/designs/widget_main.ui'
 #
-# Created by: PyQt6 UI code generator 6.9.1
+# Created by: PyQt6 UI code generator 6.10.0
 #
 # WARNING: Any manual changes made to this file will be lost when pyuic6 is
 # run again.  Do not edit this file unless you know what you are doing.
diff --git a/gotify_tray/gui/designs/widget_message.py b/gotify_tray/gui/designs/widget_message.py
index ed0d5fa..e37540b 100644
--- a/gotify_tray/gui/designs/widget_message.py
+++ b/gotify_tray/gui/designs/widget_message.py
@@ -1,6 +1,6 @@
 # Form implementation generated from reading ui file 'gotify_tray/gui/designs/widget_message.ui'
 #
-# Created by: PyQt6 UI code generator 6.9.1
+# Created by: PyQt6 UI code generator 6.10.0
 #
 # WARNING: Any manual changes made to this file will be lost when pyuic6 is
 # run again.  Do not edit this file unless you know what you are doing.
diff --git a/gotify_tray/gui/designs/widget_server.py b/gotify_tray/gui/designs/widget_server.py
index 8e84961..408b4ac 100644
--- a/gotify_tray/gui/designs/widget_server.py
+++ b/gotify_tray/gui/designs/widget_server.py
@@ -1,6 +1,6 @@
 # Form implementation generated from reading ui file 'gotify_tray/gui/designs/widget_server.ui'
 #
-# Created by: PyQt6 UI code generator 6.9.1
+# Created by: PyQt6 UI code generator 6.10.0
 #
 # WARNING: Any manual changes made to this file will be lost when pyuic6 is
 # run again.  Do not edit this file unless you know what you are doing.
diff --git a/gotify_tray/gui/designs/widget_settings.py b/gotify_tray/gui/designs/widget_settings.py
index 7056ed2..5dd120e 100644
--- a/gotify_tray/gui/designs/widget_settings.py
+++ b/gotify_tray/gui/designs/widget_settings.py
@@ -1,6 +1,6 @@
 # Form implementation generated from reading ui file 'gotify_tray/gui/designs/widget_settings.ui'
 #
-# Created by: PyQt6 UI code generator 6.9.1
+# Created by: PyQt6 UI code generator 6.10.0
 #
 # WARNING: Any manual changes made to this file will be lost when pyuic6 is
 # run again.  Do not edit this file unless you know what you are doing.
diff --git a/gotify_tray/gui/models/MessagesModel.py b/gotify_tray/gui/models/MessagesModel.py
index a7da27a..d90f9b6 100644
--- a/gotify_tray/gui/models/MessagesModel.py
+++ b/gotify_tray/gui/models/MessagesModel.py
@@ -65,7 +65,7 @@ class MessagesProxyModel(QtCore.QSortFilterProxyModel):
             return False
         if self.text_filter:
             title = (message.title or "").lower()
-            msg = message.message.lower()
+            msg = (message.message or "").lower()
             if self.text_filter not in title and self.text_filter not in msg:
                 return False
         return True
diff --git a/gotify_tray/gui/themes/__init__.py b/gotify_tray/gui/themes/__init__.py
index f8bc09a..87bb332 100644
--- a/gotify_tray/gui/themes/__init__.py
+++ b/gotify_tray/gui/themes/__init__.py
@@ -3,14 +3,21 @@ from gotify_tray.utils import get_abs_path
 
 
 themes = {
-    QtCore.Qt.ColorScheme.Dark: "dark",
-    QtCore.Qt.ColorScheme.Light: "light",
-    QtCore.Qt.ColorScheme.Unknown: "light",
+    2: "dark",  # Dark
+    1: "light",  # Light
+    0: "light",  # Unknown
 }
 
 
 def set_theme(app: QtWidgets.QApplication):
-    theme = themes.get(app.styleHints().colorScheme(), "light")
+    if hasattr(app.styleHints(), "colorScheme"):
+        color_scheme = app.styleHints().colorScheme()
+        theme = themes.get(
+            color_scheme.value if hasattr(color_scheme, "value") else color_scheme,
+            "light",
+        )
+    else:
+        theme = "light"  # Default to light theme if colorScheme not available
 
     stylesheet = ""
     with open(get_abs_path(f"gotify_tray/gui/themes/base.qss"), "r") as f:
@@ -23,5 +30,12 @@ def set_theme(app: QtWidgets.QApplication):
 
 def get_theme_file(file: str) -> str:
     app = QtCore.QCoreApplication.instance()
-    theme = themes.get(app.styleHints().colorScheme(), "light")
+    if hasattr(app.styleHints(), "colorScheme"):
+        color_scheme = app.styleHints().colorScheme()
+        theme = themes.get(
+            color_scheme.value if hasattr(color_scheme, "value") else color_scheme,
+            "light",
+        )
+    else:
+        theme = "light"  # Default to light theme if colorScheme not available
     return get_abs_path(f"gotify_tray/gui/themes/{theme}/{file}")
diff --git a/run.sh b/run.sh
new file mode 100755
index 0000000..35f2194
--- /dev/null
+++ b/run.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# Check if virtual environment exists
+if [ ! -d "venv" ]; then
+    echo "Creating virtual environment..."
+    python3 -m venv venv
+    echo "Installing dependencies..."
+    source venv/bin/activate
+    pip install -r requirements.txt
+else
+    source venv/bin/activate
+fi
+
+# Run the application
+python -m gotify_tray
\ No newline at end of file