diff --git a/modules/cms/assets/css/october.components.css b/modules/cms/assets/css/october.components.css
index 121845084..b4994db8c 100644
--- a/modules/cms/assets/css/october.components.css
+++ b/modules/cms/assets/css/october.components.css
@@ -118,6 +118,15 @@ div.control-componentlist.has-components {
 div.control-componentlist div.layout {
   width: auto;
 }
+div.control-componentlist div.components div.layout-cell.error-component {
+  background: #ab2a1c;
+}
+div.control-componentlist div.components div.layout-cell.error-component > div {
+  color: #ffffff;
+}
+div.control-componentlist div.components div.layout-cell.error-component > div:after {
+  color: #ab2a1c;
+}
 div.control-componentlist div.components div.layout-cell:first-child {
   border-bottom-left-radius: 3px;
   border-top-left-radius: 3px;
diff --git a/modules/cms/assets/js/october.cmspage.js b/modules/cms/assets/js/october.cmspage.js
index e2da4b975..bf14df02b 100644
--- a/modules/cms/assets/js/october.cmspage.js
+++ b/modules/cms/assets/js/october.cmspage.js
@@ -87,6 +87,18 @@
                 setPageTitle('')
         })
 
+        /*
+         * Listen for the onBeforeRequest event
+         */
+        $('#cms-master-tabs').on('oc.beforeRequest', function(event) {
+            var $form = $(event.target)
+
+            if ( $('.components .layout-cell.error-component', $form).length > 0) {
+                if (!confirm('The form contains unknown components. Their properties will be lost on save. Do you want to save the form?'))
+                    event.preventDefault()
+            }
+        })
+
         /*
          * Listen for the tabs "shown" event to track the current template in the list
          */
diff --git a/modules/cms/assets/less/october.components.less b/modules/cms/assets/less/october.components.less
index 3c8c888ca..40589f41d 100644
--- a/modules/cms/assets/less/october.components.less
+++ b/modules/cms/assets/less/october.components.less
@@ -11,6 +11,8 @@
 @color-component-hover-text:    #ffffff;
 @color-component-placeholder:   #e0e0e0;
 @color-group-bg:                #f1f3f4;
+@color-error-component-bg:      #ab2a1c;
+@color-error-component-text:    #ffffff;
 
 .component-lego-icon() {
     position: absolute;
@@ -117,6 +119,18 @@ div.control-componentlist {
 
     div.components {
         div.layout-cell {
+            &.error-component {
+                background: @color-error-component-bg;
+
+                > div {
+                    color: @color-error-component-text;
+
+                    &:after {
+                        color: @color-error-component-bg;
+                    }
+                }
+            }
+
             &:first-child {
                 .border-left-radius(3px);
             }
diff --git a/modules/cms/classes/CmsCompoundObject.php b/modules/cms/classes/CmsCompoundObject.php
index e5af60ff5..c37c46d7f 100644
--- a/modules/cms/classes/CmsCompoundObject.php
+++ b/modules/cms/classes/CmsCompoundObject.php
@@ -133,8 +133,8 @@ class CmsCompoundObject extends CmsObject
 
             $settingParts = explode(' ', $setting);
             $settingName = $settingParts[0];
-            if (!$manager->hasComponent($settingName))
-                continue;
+            // if (!$manager->hasComponent($settingName))
+            //     continue;
 
             $components[$setting] = $value;
             unset($this->settings[$setting]);
diff --git a/modules/cms/classes/ComponentBase.php b/modules/cms/classes/ComponentBase.php
index 2a37180d6..7e6d38eed 100644
--- a/modules/cms/classes/ComponentBase.php
+++ b/modules/cms/classes/ComponentBase.php
@@ -39,6 +39,18 @@ abstract class ComponentBase extends Extendable
      */
     public $pluginIcon;
 
+    /**
+     * @var string Component CSS class name for the back-end page/layout component list.
+     * This field is used by the CMS internally.
+     */
+    public $componentCssClass;
+
+    /**
+     * @var boolean Determines whether Inspector can be used with the component.
+     * This field is used by the CMS internally.
+     */
+    public $inspectorEnabled = true;
+
     /**
      * @var string Specifies the component directory name.
      */
diff --git a/modules/cms/classes/ComponentManager.php b/modules/cms/classes/ComponentManager.php
index 76168cfd8..8674c7a33 100644
--- a/modules/cms/classes/ComponentManager.php
+++ b/modules/cms/classes/ComponentManager.php
@@ -3,6 +3,7 @@
 use Str;
 use Illuminate\Container\Container;
 use System\Classes\PluginManager;
+use System\Classes\SystemException;
 
 /**
  * Component manager
@@ -179,10 +180,10 @@ class ComponentManager
     {
         $className = $this->resolve($name);
         if (!$className)
-            return null;
+            throw new SystemException(sprintf('Class name is not registered for the component %s. Check the component plugin.', $name));
 
         if (!class_exists($className))
-            throw new \Exception('Component class not found '.$className);
+            throw new SystemException(sprintf('Component class not found %s.Check the component plugin.', $className));
 
         $component = new $className($cmsObject, $properties);
         $component->name = $name;
diff --git a/modules/cms/classes/UnknownComponent.php b/modules/cms/classes/UnknownComponent.php
new file mode 100644
index 000000000..5d9c9c5ed
--- /dev/null
+++ b/modules/cms/classes/UnknownComponent.php
@@ -0,0 +1,29 @@
+<?php namespace Cms\Classes;
+
+use Cms\Classes\ComponentBase;
+use Cms\Classes\CodeBase;
+
+class UnknownComponent extends ComponentBase
+{
+    protected $errorMessage;
+
+    /**
+     * {@inheritDoc}
+     */
+    public function __construct($cmsObject, $properties, $errorMessage)
+    {
+        $this->errorMessage = $errorMessage;
+        $this->componentCssClass = 'error-component';
+        $this->inspectorEnabled = false;
+
+        parent::__construct($cmsObject, $properties);
+    }
+
+    public function componentDetails()
+    {
+        return [
+            'name'        => 'Uknown component',
+            'description' => $this->errorMessage
+        ];
+    }
+}
\ No newline at end of file
diff --git a/modules/cms/formwidgets/Components.php b/modules/cms/formwidgets/Components.php
index 483831191..b52df6785 100644
--- a/modules/cms/formwidgets/Components.php
+++ b/modules/cms/formwidgets/Components.php
@@ -3,7 +3,9 @@
 use Backend\Classes\FormWidgetBase;
 use Cms\Classes\ComponentManager;
 use Cms\Classes\ComponentHelpers;
+use Cms\Classes\UnknownComponent;
 use Lang;
+use Exception;
 
 /**
  * Component Builder
@@ -36,15 +38,22 @@ class Components extends FormWidgetBase
         foreach ($this->model->settings['components'] as $name=>$properties) {
             list($name, $alias) = strpos($name, ' ') ? explode(' ', $name) : [$name, $name];
 
-            $componentObj = $manager->makeComponent($name, null, $properties);
-            $componentObj->alias = $alias;
-            $componentObj->pluginIcon = 'icon-puzzle-piece';
+            try {
+                $componentObj = $manager->makeComponent($name, null, $properties);
 
-            $plugin = $manager->findComponentPlugin($componentObj);
-            if ($plugin) {
-                $pluginDetails = $plugin->pluginDetails();
-                if (isset($pluginDetails['icon']))
-                    $componentObj->pluginIcon = $pluginDetails['icon'];
+                $componentObj->alias = $alias;
+                $componentObj->pluginIcon = 'icon-puzzle-piece';
+
+                $plugin = $manager->findComponentPlugin($componentObj);
+                if ($plugin) {
+                    $pluginDetails = $plugin->pluginDetails();
+                    if (isset($pluginDetails['icon']))
+                        $componentObj->pluginIcon = $pluginDetails['icon'];
+                }
+            } catch (Exception $ex) {
+                $componentObj = new UnknownComponent(null, $properties, $ex->getMessage());
+                $componentObj->alias = $alias;
+                $componentObj->pluginIcon = 'icon-bug';
             }
 
             $result[] = $componentObj;
diff --git a/modules/cms/formwidgets/components/partials/_formcomponents.htm b/modules/cms/formwidgets/components/partials/_formcomponents.htm
index e065303b1..0c769d9cd 100644
--- a/modules/cms/formwidgets/components/partials/_formcomponents.htm
+++ b/modules/cms/formwidgets/components/partials/_formcomponents.htm
@@ -2,15 +2,21 @@
     <div class="components" data-control="toolbar">
         <div class="layout">
             <?php foreach ($components as $component): ?>
-                <div class="layout-cell">
-                    <div class="<?= 'oc-'.$component->pluginIcon ?> layout-relative" data-inspectable data-inspector-title="<?= $name = e($this->getComponentName($component)) ?>" data-inspector-description="<?= $description = e($this->getComponentDescription($component)) ?>" data-inspector-config="<?= e($this->getComponentsPropertyConfig($component)) ?>" data-inspector-class="<?= get_class($component) ?>">
-                        <span class="name"><?= $name ?></span>
-                        <span class="description"><?= $description ?></span>
-                        <span class="alias oc-icon-code"><?= e($component->alias) ?></span>
-                        <input type="hidden" name="component_properties[]" data-inspector-values value="<?= e($this->getComponentPropertyValues($component)) ?>"/>
-                        <input type="hidden" name="component_names[]" value="<?= e($component->name) ?>"></input>
-                        <input type="hidden" name="component_aliases[]" value="<?= e($component->alias) ?>"></input>
-                        <a href="#" class="remove">&times;</a>
+                <div class="layout-cell <?= e($component->componentCssClass) ?>">
+                    <div 
+                        class="<?= 'oc-'.$component->pluginIcon ?> layout-relative" 
+                        <?php if ($component->inspectorEnabled): ?>data-inspectable<?php endif ?>
+                        data-inspector-title="<?= $name = e($this->getComponentName($component)) ?>"
+                        data-inspector-description="<?= $description = e($this->getComponentDescription($component)) ?>"
+                        data-inspector-config="<?= e($this->getComponentsPropertyConfig($component)) ?>"
+                        data-inspector-class="<?= get_class($component) ?>">
+                            <span class="name"><?= $name ?></span>
+                            <span class="description"><?= $description ?></span>
+                            <span class="alias oc-icon-code"><?= e($component->alias) ?></span>
+                            <input type="hidden" name="component_properties[]" data-inspector-values value="<?= e($this->getComponentPropertyValues($component)) ?>"/>
+                            <input type="hidden" name="component_names[]" value="<?= e($component->name) ?>"></input>
+                            <input type="hidden" name="component_aliases[]" value="<?= e($component->alias) ?>"></input>
+                            <a href="#" class="remove">&times;</a>
                     </div>
                 </div>
             <?php endforeach ?>
diff --git a/modules/system/assets/js/framework.js b/modules/system/assets/js/framework.js
index b9c28a623..3b5e0c4e0 100644
--- a/modules/system/assets/js/framework.js
+++ b/modules/system/assets/js/framework.js
@@ -45,7 +45,9 @@ if (window.jQuery === undefined)
             loading = options.loading !== undefined && options.loading.length ? $(options.loading) : null,
             isRedirect = options.redirect !== undefined && options.redirect.length
 
-        form.trigger('oc.beforeRequest', context)
+        var _event = jQuery.Event('oc.beforeRequest')
+        form.trigger(_event, context)
+        if (_event.isDefaultPrevented()) return
 
         var data = [form.serialize()]