diff --git a/src/Umbraco.Core/Collections/EventClearingObservableCollection.cs b/src/Umbraco.Core/Collections/EventClearingObservableCollection.cs
new file mode 100644
index 0000000000..af25cc1b4a
--- /dev/null
+++ b/src/Umbraco.Core/Collections/EventClearingObservableCollection.cs
@@ -0,0 +1,41 @@
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+
+namespace Umbraco.Core.Collections
+{
+    /// <summary>
+    /// Allows clearing all event handlers
+    /// </summary>
+    /// <typeparam name="TValue"></typeparam>
+    public class EventClearingObservableCollection<TValue> : ObservableCollection<TValue>, INotifyCollectionChanged
+    {
+        public EventClearingObservableCollection()
+        {
+        }
+
+        public EventClearingObservableCollection(List<TValue> list) : base(list)
+        {
+        }
+
+        public EventClearingObservableCollection(IEnumerable<TValue> collection) : base(collection)
+        {
+        }
+
+        // need to explicitly implement with event accessor syntax in order to override in order to to clear
+        // c# events are weird, they do not behave the same way as other c# things that are 'virtual',
+        // a good article is here: https://medium.com/@unicorn_dev/virtual-events-in-c-something-went-wrong-c6f6f5fbe252
+        // and https://stackoverflow.com/questions/2268065/c-sharp-language-design-explicit-interface-implementation-of-an-event
+        private NotifyCollectionChangedEventHandler _changed;
+        event NotifyCollectionChangedEventHandler INotifyCollectionChanged.CollectionChanged
+        {
+            add { _changed += value; }
+            remove { _changed -= value; }
+        }
+
+        /// <summary>
+        /// Clears all event handlers for the <see cref="CollectionChanged"/> event
+        /// </summary>
+        public void ClearCollectionChangedEvents() => _changed = null;
+    }
+}
diff --git a/src/Umbraco.Core/Collections/ObservableDictionary.cs b/src/Umbraco.Core/Collections/ObservableDictionary.cs
index c6aedab377..fd9e469f07 100644
--- a/src/Umbraco.Core/Collections/ObservableDictionary.cs
+++ b/src/Umbraco.Core/Collections/ObservableDictionary.cs
@@ -1,11 +1,14 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.ComponentModel;
 using System.Linq;
 using System.Runtime.Serialization;
 
 namespace Umbraco.Core.Collections
 {
+
     /// <summary>
     /// An ObservableDictionary
     /// </summary>
@@ -15,7 +18,7 @@ namespace Umbraco.Core.Collections
     /// </remarks>
     /// <typeparam name="TValue">The type of elements contained in the BindableCollection</typeparam>
     /// <typeparam name="TKey">The type of the indexing key</typeparam>
-    public class ObservableDictionary<TKey, TValue> : ObservableCollection<TValue>, IReadOnlyDictionary<TKey, TValue>, IDictionary<TKey, TValue>
+    public class ObservableDictionary<TKey, TValue> : ObservableCollection<TValue>, IReadOnlyDictionary<TKey, TValue>, IDictionary<TKey, TValue>, INotifyCollectionChanged
     {
         protected Dictionary<TKey, int> Indecies { get; }
         protected Func<TValue, TKey> KeySelector { get; }
@@ -74,6 +77,22 @@ namespace Umbraco.Core.Collections
 
         #endregion
 
+        // need to explicitly implement with event accessor syntax in order to override in order to to clear
+        // c# events are weird, they do not behave the same way as other c# things that are 'virtual',
+        // a good article is here: https://medium.com/@unicorn_dev/virtual-events-in-c-something-went-wrong-c6f6f5fbe252
+        // and https://stackoverflow.com/questions/2268065/c-sharp-language-design-explicit-interface-implementation-of-an-event
+        private NotifyCollectionChangedEventHandler _changed;
+        event NotifyCollectionChangedEventHandler INotifyCollectionChanged.CollectionChanged
+        {
+            add { _changed += value; }
+            remove { _changed -= value; }
+        }
+
+        /// <summary>
+        /// Clears all <see cref="CollectionChanged"/> event handlers
+        /// </summary>
+        public void ClearCollectionChangedEvents() => _changed = null;
+
         public bool ContainsKey(TKey key)
         {
             return Indecies.ContainsKey(key);
diff --git a/src/Umbraco.Core/Models/Content.cs b/src/Umbraco.Core/Models/Content.cs
index c5930bf998..04f49e704e 100644
--- a/src/Umbraco.Core/Models/Content.cs
+++ b/src/Umbraco.Core/Models/Content.cs
@@ -98,10 +98,15 @@ namespace Umbraco.Core.Models
             set
             {
                 if (_schedule != null)
-                    _schedule.CollectionChanged -= ScheduleCollectionChanged;
+                {
+                    _schedule.ClearCollectionChangedEvents();
+                }
+                    
                 SetPropertyValueAndDetectChanges(value, ref _schedule, nameof(ContentSchedule));
                 if (_schedule != null)
+                {
                     _schedule.CollectionChanged += ScheduleCollectionChanged;
+                }   
             }
         }
 
@@ -223,10 +228,16 @@ namespace Umbraco.Core.Models
             }
             set
             {
-                if (_publishInfos != null) _publishInfos.CollectionChanged -= PublishNamesCollectionChanged;
+                if (_publishInfos != null)
+                {
+                    _publishInfos.ClearCollectionChangedEvents();
+                }
+
                 _publishInfos = value;
                 if (_publishInfos != null)
+                {
                     _publishInfos.CollectionChanged += PublishNamesCollectionChanged;
+                }   
             }
         }
 
@@ -321,7 +332,7 @@ namespace Umbraco.Core.Models
             else
                 Properties.EnsurePropertyTypes(contentType.CompositionPropertyTypes);
 
-            Properties.CollectionChanged -= PropertiesChanged; // be sure not to double add
+            Properties.ClearCollectionChangedEvents(); // be sure not to double add
             Properties.CollectionChanged += PropertiesChanged;
         }
 
@@ -438,7 +449,7 @@ namespace Umbraco.Core.Models
             //if culture infos exist then deal with event bindings
             if (clonedContent._publishInfos != null)
             {
-                clonedContent._publishInfos.CollectionChanged -= PublishNamesCollectionChanged;          //clear this event handler if any
+                clonedContent._publishInfos.ClearCollectionChangedEvents();          //clear this event handler if any
                 clonedContent._publishInfos = (ContentCultureInfosCollection)_publishInfos.DeepClone(); //manually deep clone
                 clonedContent._publishInfos.CollectionChanged += clonedContent.PublishNamesCollectionChanged;    //re-assign correct event handler
             }
@@ -446,7 +457,7 @@ namespace Umbraco.Core.Models
             //if properties exist then deal with event bindings
             if (clonedContent._schedule != null)
             {
-                clonedContent._schedule.CollectionChanged -= ScheduleCollectionChanged;         //clear this event handler if any
+                clonedContent._schedule.ClearCollectionChangedEvents();         //clear this event handler if any
                 clonedContent._schedule = (ContentScheduleCollection)_schedule.DeepClone();     //manually deep clone
                 clonedContent._schedule.CollectionChanged += clonedContent.ScheduleCollectionChanged;   //re-assign correct event handler
             }
diff --git a/src/Umbraco.Core/Models/ContentBase.cs b/src/Umbraco.Core/Models/ContentBase.cs
index d02ea82012..cbdee479fe 100644
--- a/src/Umbraco.Core/Models/ContentBase.cs
+++ b/src/Umbraco.Core/Models/ContentBase.cs
@@ -138,7 +138,11 @@ namespace Umbraco.Core.Models
             get => _properties;
             set
             {
-                if (_properties != null) _properties.CollectionChanged -= PropertiesChanged;
+                if (_properties != null)
+                {
+                    _properties.ClearCollectionChangedEvents();
+                }
+
                 _properties = value;
                 _properties.CollectionChanged += PropertiesChanged;
             }
@@ -173,10 +177,15 @@ namespace Umbraco.Core.Models
             }
             set
             {
-                if (_cultureInfos != null) _cultureInfos.CollectionChanged -= CultureInfosCollectionChanged;
+                if (_cultureInfos != null)
+                {
+                    _cultureInfos.ClearCollectionChangedEvents();
+                }
                 _cultureInfos = value;
                 if (_cultureInfos != null)
+                {
                     _cultureInfos.CollectionChanged += CultureInfosCollectionChanged;
+                }   
             }
         }
 
@@ -479,7 +488,7 @@ namespace Umbraco.Core.Models
             //if culture infos exist then deal with event bindings
             if (clonedContent._cultureInfos != null)
             {
-                clonedContent._cultureInfos.CollectionChanged -= CultureInfosCollectionChanged;          //clear this event handler if any
+                clonedContent._cultureInfos.ClearCollectionChangedEvents();          //clear this event handler if any
                 clonedContent._cultureInfos = (ContentCultureInfosCollection)_cultureInfos.DeepClone(); //manually deep clone
                 clonedContent._cultureInfos.CollectionChanged += clonedContent.CultureInfosCollectionChanged;    //re-assign correct event handler
             }
@@ -487,7 +496,7 @@ namespace Umbraco.Core.Models
             //if properties exist then deal with event bindings
             if (clonedContent._properties != null)
             {
-                clonedContent._properties.CollectionChanged -= PropertiesChanged;         //clear this event handler if any
+                clonedContent._properties.ClearCollectionChangedEvents();         //clear this event handler if any
                 clonedContent._properties = (PropertyCollection)_properties.DeepClone(); //manually deep clone
                 clonedContent._properties.CollectionChanged += clonedContent.PropertiesChanged;   //re-assign correct event handler
             }
diff --git a/src/Umbraco.Core/Models/ContentCultureInfosCollection.cs b/src/Umbraco.Core/Models/ContentCultureInfosCollection.cs
index 9bc78fc56d..07ee661497 100644
--- a/src/Umbraco.Core/Models/ContentCultureInfosCollection.cs
+++ b/src/Umbraco.Core/Models/ContentCultureInfosCollection.cs
@@ -15,7 +15,7 @@ namespace Umbraco.Core.Models
         public ContentCultureInfosCollection()
             : base(x => x.Culture, StringComparer.InvariantCultureIgnoreCase)
         { }
-        
+
         /// <summary>
         /// Adds or updates a <see cref="ContentCultureInfos"/> instance.
         /// </summary>
diff --git a/src/Umbraco.Core/Models/ContentScheduleCollection.cs b/src/Umbraco.Core/Models/ContentScheduleCollection.cs
index 6c7dd79312..0ebcc0fe4b 100644
--- a/src/Umbraco.Core/Models/ContentScheduleCollection.cs
+++ b/src/Umbraco.Core/Models/ContentScheduleCollection.cs
@@ -14,6 +14,11 @@ namespace Umbraco.Core.Models
 
         public event NotifyCollectionChangedEventHandler CollectionChanged;
 
+        /// <summary>
+        /// Clears all <see cref="CollectionChanged"/> event handlers
+        /// </summary>
+        public void ClearCollectionChangedEvents() => CollectionChanged = null;
+
         private void OnCollectionChanged(NotifyCollectionChangedEventArgs args)
         {
             CollectionChanged?.Invoke(this, args);
diff --git a/src/Umbraco.Core/Models/ContentTypeBase.cs b/src/Umbraco.Core/Models/ContentTypeBase.cs
index 04bcb7424a..4865db428a 100644
--- a/src/Umbraco.Core/Models/ContentTypeBase.cs
+++ b/src/Umbraco.Core/Models/ContentTypeBase.cs
@@ -262,7 +262,10 @@ namespace Umbraco.Core.Models
             set
             {
                 if (_noGroupPropertyTypes != null)
-                    _noGroupPropertyTypes.CollectionChanged -= PropertyTypesChanged;
+                {
+                    _noGroupPropertyTypes.ClearCollectionChangedEvents();
+                }
+
                 _noGroupPropertyTypes = new PropertyTypeCollection(SupportsPublishing, value);
                 _noGroupPropertyTypes.CollectionChanged += PropertyTypesChanged;
                 PropertyTypesChanged(_noGroupPropertyTypes, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
@@ -480,14 +483,14 @@ namespace Umbraco.Core.Models
                 // its ignored from the auto-clone process because its return values are unions, not raw and
                 // we end up with duplicates, see: http://issues.umbraco.org/issue/U4-4842
 
-                clonedEntity._noGroupPropertyTypes.CollectionChanged -= PropertyTypesChanged;                    //clear this event handler if any
+                clonedEntity._noGroupPropertyTypes.ClearCollectionChangedEvents();                    //clear this event handler if any
                 clonedEntity._noGroupPropertyTypes = (PropertyTypeCollection) _noGroupPropertyTypes.DeepClone(); //manually deep clone
                 clonedEntity._noGroupPropertyTypes.CollectionChanged += clonedEntity.PropertyTypesChanged;              //re-assign correct event handler
             }
 
             if (clonedEntity._propertyGroups != null)
             {
-                clonedEntity._propertyGroups.CollectionChanged -= PropertyGroupsChanged;              //clear this event handler if any
+                clonedEntity._propertyGroups.ClearCollectionChangedEvents();              //clear this event handler if any
                 clonedEntity._propertyGroups = (PropertyGroupCollection) _propertyGroups.DeepClone(); //manually deep clone
                 clonedEntity._propertyGroups.CollectionChanged += clonedEntity.PropertyGroupsChanged;        //re-assign correct event handler
             }
diff --git a/src/Umbraco.Core/Models/Identity/BackOfficeIdentityUser.cs b/src/Umbraco.Core/Models/Identity/BackOfficeIdentityUser.cs
index 8dc056d555..63404bb38b 100644
--- a/src/Umbraco.Core/Models/Identity/BackOfficeIdentityUser.cs
+++ b/src/Umbraco.Core/Models/Identity/BackOfficeIdentityUser.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using System.Linq;
+using Umbraco.Core.Collections;
 using Umbraco.Core.Composing;
 using Umbraco.Core.Models.Entities;
 using Umbraco.Core.Models.Membership;
@@ -62,7 +63,7 @@ namespace Umbraco.Core.Models.Identity
             _culture = Current.Configs.Global().DefaultUILanguage; // TODO: inject
 
             // must initialize before setting groups
-            _roles = new ObservableCollection<IdentityUserRole<string>>();
+            _roles = new EventClearingObservableCollection<IdentityUserRole<string>>();
             _roles.CollectionChanged += _roles_CollectionChanged;
 
             // use the property setters - they do more than just setting a field
@@ -223,7 +224,7 @@ namespace Umbraco.Core.Models.Identity
                 _groups = value;
 
                 //now clear all roles and re-add them
-                _roles.CollectionChanged -= _roles_CollectionChanged;
+                _roles.ClearCollectionChangedEvents();
                 _roles.Clear();
                 foreach (var identityUserRole in _groups.Select(x => new IdentityUserRole<string>
                 {
@@ -299,7 +300,7 @@ namespace Umbraco.Core.Models.Identity
             _beingDirty.OnPropertyChanged(nameof(Roles));
         }
 
-        private readonly ObservableCollection<IdentityUserRole<string>> _roles;
+        private readonly EventClearingObservableCollection<IdentityUserRole<string>> _roles;
 
         /// <summary>
         /// helper method to easily add a role without having to deal with IdentityUserRole{T}
diff --git a/src/Umbraco.Core/Models/Media.cs b/src/Umbraco.Core/Models/Media.cs
index 002611c09c..87ec9196d6 100644
--- a/src/Umbraco.Core/Models/Media.cs
+++ b/src/Umbraco.Core/Models/Media.cs
@@ -77,7 +77,7 @@ namespace Umbraco.Core.Models
             else
                 Properties.EnsurePropertyTypes(contentType.CompositionPropertyTypes);
 
-            Properties.CollectionChanged -= PropertiesChanged; // be sure not to double add
+            Properties.ClearCollectionChangedEvents(); // be sure not to double add
             Properties.CollectionChanged += PropertiesChanged;
         }
     }
diff --git a/src/Umbraco.Core/Models/PropertyCollection.cs b/src/Umbraco.Core/Models/PropertyCollection.cs
index 13fbf949d6..a73df6a095 100644
--- a/src/Umbraco.Core/Models/PropertyCollection.cs
+++ b/src/Umbraco.Core/Models/PropertyCollection.cs
@@ -169,6 +169,8 @@ namespace Umbraco.Core.Models
         /// </summary>
         public event NotifyCollectionChangedEventHandler CollectionChanged;
 
+        public void ClearCollectionChangedEvents() => CollectionChanged = null;
+
         protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs args)
         {
             CollectionChanged?.Invoke(this, args);
diff --git a/src/Umbraco.Core/Models/PropertyGroup.cs b/src/Umbraco.Core/Models/PropertyGroup.cs
index 2e6da5d837..022fb6ed03 100644
--- a/src/Umbraco.Core/Models/PropertyGroup.cs
+++ b/src/Umbraco.Core/Models/PropertyGroup.cs
@@ -66,7 +66,10 @@ namespace Umbraco.Core.Models
             set
             {
                 if (_propertyTypes != null)
-                    _propertyTypes.CollectionChanged -= PropertyTypesChanged;
+                {
+                    _propertyTypes.ClearCollectionChangedEvents();
+                }
+                    
                 _propertyTypes = value;
 
                 // since we're adding this collection to this group,
@@ -100,7 +103,7 @@ namespace Umbraco.Core.Models
 
             if (clonedEntity._propertyTypes != null)
             {
-                clonedEntity._propertyTypes.CollectionChanged -= PropertyTypesChanged;             //clear this event handler if any
+                clonedEntity._propertyTypes.ClearCollectionChangedEvents();             //clear this event handler if any
                 clonedEntity._propertyTypes = (PropertyTypeCollection) _propertyTypes.DeepClone(); //manually deep clone
                 clonedEntity._propertyTypes.CollectionChanged += clonedEntity.PropertyTypesChanged;       //re-assign correct event handler
             }
diff --git a/src/Umbraco.Core/Models/PropertyGroupCollection.cs b/src/Umbraco.Core/Models/PropertyGroupCollection.cs
index 5422dfb792..973147b3fb 100644
--- a/src/Umbraco.Core/Models/PropertyGroupCollection.cs
+++ b/src/Umbraco.Core/Models/PropertyGroupCollection.cs
@@ -160,6 +160,11 @@ namespace Umbraco.Core.Models
 
         public event NotifyCollectionChangedEventHandler CollectionChanged;
 
+        /// <summary>
+        /// Clears all <see cref="CollectionChanged"/> event handlers
+        /// </summary>
+        public void ClearCollectionChangedEvents() => CollectionChanged = null;
+
         protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs args)
         {
             CollectionChanged?.Invoke(this, args);
diff --git a/src/Umbraco.Core/Models/PropertyTypeCollection.cs b/src/Umbraco.Core/Models/PropertyTypeCollection.cs
index 6e41f0d12b..cc9d00fa5d 100644
--- a/src/Umbraco.Core/Models/PropertyTypeCollection.cs
+++ b/src/Umbraco.Core/Models/PropertyTypeCollection.cs
@@ -162,7 +162,11 @@ namespace Umbraco.Core.Models
         }
 
         public event NotifyCollectionChangedEventHandler CollectionChanged;
-
+        
+        /// <summary>
+        /// Clears all <see cref="CollectionChanged"/> event handlers
+        /// </summary>
+        public void ClearCollectionChangedEvents() => CollectionChanged = null;
         protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs args)
         {
             CollectionChanged?.Invoke(this, args);
diff --git a/src/Umbraco.Core/Models/PublicAccessEntry.cs b/src/Umbraco.Core/Models/PublicAccessEntry.cs
index cfb30de147..cc86b797cb 100644
--- a/src/Umbraco.Core/Models/PublicAccessEntry.cs
+++ b/src/Umbraco.Core/Models/PublicAccessEntry.cs
@@ -4,6 +4,7 @@ using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using System.Linq;
 using System.Runtime.Serialization;
+using Umbraco.Core.Collections;
 using Umbraco.Core.Models.Entities;
 
 namespace Umbraco.Core.Models
@@ -12,7 +13,7 @@ namespace Umbraco.Core.Models
     [DataContract(IsReference = true)]
     public class PublicAccessEntry : EntityBase
     {
-        private readonly ObservableCollection<PublicAccessRule> _ruleCollection;
+        private readonly EventClearingObservableCollection<PublicAccessRule> _ruleCollection;
         private int _protectedNodeId;
         private int _noAccessNodeId;
         private int _loginNodeId;
@@ -28,7 +29,7 @@ namespace Umbraco.Core.Models
             NoAccessNodeId = noAccessNode.Id;
             _protectedNodeId = protectedNode.Id;
 
-            _ruleCollection = new ObservableCollection<PublicAccessRule>(ruleCollection);
+            _ruleCollection = new EventClearingObservableCollection<PublicAccessRule>(ruleCollection);
             _ruleCollection.CollectionChanged += _ruleCollection_CollectionChanged;
 
             foreach (var rule in _ruleCollection)
@@ -44,7 +45,7 @@ namespace Umbraco.Core.Models
             NoAccessNodeId = noAccessNodeId;
             _protectedNodeId = protectedNodeId;
 
-            _ruleCollection = new ObservableCollection<PublicAccessRule>(ruleCollection);
+            _ruleCollection = new EventClearingObservableCollection<PublicAccessRule>(ruleCollection);
             _ruleCollection.CollectionChanged += _ruleCollection_CollectionChanged;
 
             foreach (var rule in _ruleCollection)
@@ -148,7 +149,7 @@ namespace Umbraco.Core.Models
 
             if (cloneEntity._ruleCollection != null)
             {
-                cloneEntity._ruleCollection.CollectionChanged -= _ruleCollection_CollectionChanged;       //clear this event handler if any
+                cloneEntity._ruleCollection.ClearCollectionChangedEvents();       //clear this event handler if any
                 cloneEntity._ruleCollection.CollectionChanged += cloneEntity._ruleCollection_CollectionChanged; //re-assign correct event handler
             }
         }
diff --git a/src/Umbraco.Core/Umbraco.Core.csproj b/src/Umbraco.Core/Umbraco.Core.csproj
index b7b9867618..9d4a3b3e75 100755
--- a/src/Umbraco.Core/Umbraco.Core.csproj
+++ b/src/Umbraco.Core/Umbraco.Core.csproj
@@ -129,6 +129,7 @@
     -->
     <Compile Include="AssemblyExtensions.cs" />
     <Compile Include="Constants-SqlTemplates.cs" />
+    <Compile Include="Collections\EventClearingObservableCollection.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\Models\ContentTypeDto80.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\Models\PropertyDataDto80.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\Models\PropertyTypeDto80.cs" />