diff --git a/cura/Settings/MachineManager.py b/cura/Settings/MachineManager.py
index 1503fb5f39..851e852800 100755
--- a/cura/Settings/MachineManager.py
+++ b/cura/Settings/MachineManager.py
@@ -847,6 +847,24 @@ class MachineManager(QObject):
 
         return result
 
+    @pyqtProperty(bool, notify = currentConfigurationChanged)
+    def variantCoreUsableForFactor4(self) -> bool:
+        """The selected core is usable if it is in second extruder of Factor4
+        """
+        result = True
+        if not self._global_container_stack:
+            return result
+        if self.activeMachine.definition.id != "ultimaker_factor4":
+            return result
+
+        for extruder_container in self._global_container_stack.extruderList:
+            if extruder_container.definition.id.startswith("ultimaker_factor4_extruder_right"):
+                if extruder_container.material == empty_material_container:
+                    return True
+                if extruder_container.variant.id.startswith("ultimaker_factor4_bb"):
+                    return False
+        return True
+
     @pyqtSlot(str, result = str)
     def getDefinitionByMachineId(self, machine_id: str) -> Optional[str]:
         """Get the Definition ID of a machine (specified by ID)
diff --git a/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml b/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml
index d1bf323e7d..7acba1e103 100644
--- a/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml
+++ b/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml
@@ -311,10 +311,11 @@ Item
             {
                 id: warnings
                 height: visible ? childrenRect.height : 0
-                visible: buildplateCompatibilityError || buildplateCompatibilityWarning
+                visible: buildplateCompatibilityError || buildplateCompatibilityWarning || coreCompatibilityWarning
 
                 property bool buildplateCompatibilityError: !Cura.MachineManager.variantBuildplateCompatible && !Cura.MachineManager.variantBuildplateUsable
                 property bool buildplateCompatibilityWarning: Cura.MachineManager.variantBuildplateUsable
+                property bool coreCompatibilityWarning: !Cura.MachineManager.variantCoreUsableForFactor4
 
                 // This is a space holder aligning the warning messages.
                 UM.Label
@@ -336,7 +337,7 @@ Item
                         width: UM.Theme.getSize("section_icon").width
                         height: UM.Theme.getSize("section_icon").height
                         color: UM.Theme.getColor("material_compatibility_warning")
-                        visible: !Cura.MachineManager.isCurrentSetupSupported || warnings.buildplateCompatibilityError || warnings.buildplateCompatibilityWarning
+                        visible: !Cura.MachineManager.isCurrentSetupSupported || warnings.buildplateCompatibilityError || warnings.buildplateCompatibilityWarning || warnings.coreCompatibilityWarning
                     }
 
                     UM.Label
@@ -349,6 +350,17 @@ Item
                         visible: CuraSDKVersion == "dev" ? false : warnings.buildplateCompatibilityError || warnings.buildplateCompatibilityWarning
                         wrapMode: Text.WordWrap
                     }
+
+                    UM.Label
+                    {
+                        id: coreCompatibilityLabel
+                        anchors.left: warningImage.right
+                        anchors.leftMargin: UM.Theme.getSize("default_margin").width
+                        width: selectors.controlWidth - warningImage.width - UM.Theme.getSize("default_margin").width
+                        text: catalog.i18nc("@label", "Combination not recommended. Load BB core to slot 1 (left) for better reliability.")
+                        visible: warnings.coreCompatibilityWarning
+                        wrapMode: Text.WordWrap
+                    }
                 }
             }
         }
diff --git a/resources/themes/cura-dark/theme.json b/resources/themes/cura-dark/theme.json
index 64c3e002a9..699b4537c3 100644
--- a/resources/themes/cura-dark/theme.json
+++ b/resources/themes/cura-dark/theme.json
@@ -179,6 +179,8 @@
 
         "material_compatibility_warning": [255, 255, 255, 255],
 
+        "core_compatibility_warning": [255, 255, 255, 255],
+
         "quality_slider_available": [255, 255, 255, 255],
 
         "monitor_printer_family_tag": [86, 86, 106, 255],
diff --git a/resources/themes/cura-light/theme.json b/resources/themes/cura-light/theme.json
index 8f3f9076c5..db2aebcd8f 100644
--- a/resources/themes/cura-light/theme.json
+++ b/resources/themes/cura-light/theme.json
@@ -349,6 +349,7 @@
         "setting_validation_ok": "background_2",
 
         "material_compatibility_warning": [243, 166, 59, 255],
+        "core_compatibility_warning": [243, 166, 59, 255],
 
         "progressbar_background": [245, 245, 245, 255],
         "progressbar_control": [50, 130, 255, 255],