diff --git a/bec_widgets/widgets/monitor/config_dialog.py b/bec_widgets/widgets/monitor/config_dialog.py
index e04ac736..1641c11c 100644
--- a/bec_widgets/widgets/monitor/config_dialog.py
+++ b/bec_widgets/widgets/monitor/config_dialog.py
@@ -13,6 +13,11 @@ from qtpy.QtWidgets import (
 )
 
 from bec_widgets.utils.yaml_dialog import load_yaml, save_yaml
+from bec_widgets.validation import MonitorConfigValidator
+from pydantic import ValidationError
+from qtpy.QtWidgets import QApplication, QMessageBox
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
+
 
 current_path = os.path.dirname(__file__)
 Ui_Form, BaseClass = uic.loadUiType(os.path.join(current_path, "config_dialog.ui"))
@@ -168,10 +173,25 @@ CONFIG_SCAN_MODE = {
 class ConfigDialog(QWidget, Ui_Form):
     config_updated = pyqtSignal(dict)
 
-    def __init__(self, default_config=None):
+    def __init__(
+        self,
+        client=None,
+        default_config=None,
+        skip_validation: bool = False,
+    ):
         super(ConfigDialog, self).__init__()
         self.setupUi(self)
 
+        # Client
+        bec_dispatcher = BECDispatcher()
+        self.client = bec_dispatcher.client if client is None else client
+        self.dev = self.client.device_manager.devices
+
+        # Init validator
+        self.skip_validation = skip_validation
+        if self.skip_validation is False:
+            self.validator = MonitorConfigValidator(self.dev)
+
         # Connect the Ok/Apply/Cancel buttons
         self.pushButton_ok.clicked.connect(self.apply_and_close)
         self.pushButton_apply.clicked.connect(self.apply_config)
@@ -522,8 +542,45 @@ class ConfigDialog(QWidget, Ui_Form):
 
     def apply_and_close(self):
         new_config = self.apply_config()
-        self.config_updated.emit(new_config)
-        self.close()
+        if self.skip_validation is True:
+            self.config_updated.emit(new_config)
+            self.close()
+        else:
+            try:
+                validated_config = self.validator.validate_monitor_config(new_config)
+                approved_config = validated_config.model_dump()
+                self.config_updated.emit(approved_config)
+                self.close()
+            except ValidationError as e:
+                error_str = str(e)
+                formatted_error_message = ConfigDialog.format_validation_error(error_str)
+
+                # Display the formatted error message in a popup
+                QMessageBox.critical(self, "Configuration Error", formatted_error_message)
+
+    @staticmethod
+    def format_validation_error(error_str: str) -> str:
+        """
+        Format the validation error string to be displayed in a popup.
+        Args:
+            error_str(str): Error string from the validation error.
+        """
+        error_lines = error_str.split("\n")
+        # The first line contains the number of errors.
+        error_header = f"<p><b>{error_lines[0]}</b></p><hr>"
+
+        formatted_error_message = error_header
+        # Skip the first line as it's the header.
+        error_details = error_lines[1:]
+
+        # Iterate through pairs of lines (each error's two lines).
+        for i in range(0, len(error_details), 2):
+            location = error_details[i]
+            message = error_details[i + 1] if i + 1 < len(error_details) else ""
+
+            formatted_error_message += f"<p><b>{location}</b><br>{message}</p><hr>"
+
+        return formatted_error_message
 
 
 if __name__ == "__main__":  # pragma: no cover
diff --git a/bec_widgets/widgets/monitor/monitor.py b/bec_widgets/widgets/monitor/monitor.py
index 4b7d70fd..840f0dd7 100644
--- a/bec_widgets/widgets/monitor/monitor.py
+++ b/bec_widgets/widgets/monitor/monitor.py
@@ -309,7 +309,7 @@ class BECMonitor(pg.GraphicsLayoutWidget):
         self.enable_crosshair = enable_crosshair
 
         # Displayed Data
-        self.database = {}
+        self.database = None
 
         self.crosshairs = None
         self.plots = None
@@ -352,6 +352,9 @@ class BECMonitor(pg.GraphicsLayoutWidget):
         # Initialize the UI
         self._init_ui(self.plot_settings["num_columns"])
 
+        if self.scanID is not None:
+            self.replot_last_scan()
+
     def _init_database(self, plot_data_config: dict, source_type_to_init=None) -> dict:
         """
         Initializes or updates the database for the PlotApp.
@@ -601,7 +604,9 @@ class BECMonitor(pg.GraphicsLayoutWidget):
         """Show the configuration dialog."""
         from bec_widgets.widgets import ConfigDialog
 
-        dialog = ConfigDialog(default_config=self.config)
+        dialog = ConfigDialog(
+            client=self.client, default_config=self.config, skip_validation=self.skip_validation
+        )
         dialog.config_updated.connect(self.on_config_update)
         dialog.show()
 
@@ -772,6 +777,13 @@ class BECMonitor(pg.GraphicsLayoutWidget):
                 else:
                     print(f"No data found for {device_name} {entry}")
 
+    def replot_last_scan(self):
+        """
+        Replot the last scan.
+        """
+        self.scan_segment_update()
+        self.update_plot(source_type="scan_segment")
+
     @pyqtSlot(dict)
     def on_data_from_redis(self, msg) -> None:
         """
diff --git a/tests/test_config_dialog.py b/tests/test_config_dialog.py
index 6d9bc9c9..48db677a 100644
--- a/tests/test_config_dialog.py
+++ b/tests/test_config_dialog.py
@@ -1,4 +1,6 @@
 import os
+from unittest.mock import MagicMock
+
 import yaml
 
 import pytest
@@ -15,9 +17,73 @@ def load_test_config(config_name):
     return config
 
 
+class FakeDevice:
+    """Fake minimal positioner class for testing."""
+
+    def __init__(self, name, enabled=True):
+        self.name = name
+        self.enabled = enabled
+        self.signals = {self.name: {"value": 1.0}}
+        self.description = {self.name: {"source": self.name}}
+
+    def __contains__(self, item):
+        return item == self.name
+
+    @property
+    def _hints(self):
+        return [self.name]
+
+    def set_value(self, fake_value: float = 1.0) -> None:
+        """
+        Setup fake value for device readout
+        Args:
+            fake_value(float): Desired fake value
+        """
+        self.signals[self.name]["value"] = fake_value
+
+    def describe(self) -> dict:
+        """
+        Get the description of the device
+        Returns:
+            dict: Description of the device
+        """
+        return self.description
+
+
+def get_mocked_device(device_name: str):
+    """
+    Helper function to mock the devices
+    Args:
+        device_name(str): Name of the device to mock
+    """
+    return FakeDevice(name=device_name, enabled=True)
+
+
 @pytest.fixture(scope="function")
-def config_dialog(qtbot):
-    widget = ConfigDialog()
+def mocked_client():
+    # Create a dictionary of mocked devices
+    device_names = ["samx", "gauss_bpm", "gauss_adc1", "gauss_adc2", "gauss_adc3", "bpm4i"]
+    mocked_devices = {name: get_mocked_device(name) for name in device_names}
+
+    # Create a MagicMock object
+    client = MagicMock()
+
+    # Mock the device_manager.devices attribute
+    client.device_manager.devices = MagicMock()
+    client.device_manager.devices.__getitem__.side_effect = lambda x: mocked_devices.get(x)
+    client.device_manager.devices.__contains__.side_effect = lambda x: x in mocked_devices
+
+    # Set each device as an attribute of the mock
+    for name, device in mocked_devices.items():
+        setattr(client.device_manager.devices, name, device)
+
+    return client
+
+
+@pytest.fixture(scope="function")
+def config_dialog(qtbot, mocked_client):
+    client = mocked_client
+    widget = ConfigDialog(client=client)
     qtbot.addWidget(widget)
     qtbot.waitExposed(widget)
     yield widget