diff --git a/src/Umbraco.Core/DependencyInjection/ServiceCollectionExtensions.cs b/src/Umbraco.Core/DependencyInjection/ServiceCollectionExtensions.cs
index 5cb9a7137f..6c806ce0db 100644
--- a/src/Umbraco.Core/DependencyInjection/ServiceCollectionExtensions.cs
+++ b/src/Umbraco.Core/DependencyInjection/ServiceCollectionExtensions.cs
@@ -7,6 +7,20 @@ namespace Umbraco.Extensions
 {
     public static class ServiceCollectionExtensions
     {
+        /// <summary>
+        /// Adds a service of type <typeparamref name="TService"/> with an implementation type of <typeparamref name="TImplementing"/> to the specified <see cref="IServiceCollection"/>.
+        /// </summary>
+        /// <remarks>
+        /// Removes all previous registrations for the type <typeparamref name="TService"/>.
+        /// </remarks>
+        public static void AddUnique<TService, TImplementing>(
+            this IServiceCollection services)
+            where TService : class
+            where TImplementing : class, TService
+        {
+            AddUnique<TService, TImplementing>(services, ServiceLifetime.Singleton);
+        }
+
         /// <summary>
         /// Adds a service of type <typeparamref name="TService"/> with an implementation type of <typeparamref name="TImplementing"/> to the specified <see cref="IServiceCollection"/>.
         /// </summary>
@@ -15,7 +29,7 @@ namespace Umbraco.Extensions
         /// </remarks>
         public static void AddUnique<TService, TImplementing>(
             this IServiceCollection services,
-            ServiceLifetime lifetime = ServiceLifetime.Singleton)
+            ServiceLifetime lifetime)
             where TService : class
             where TImplementing : class, TService
         {
diff --git a/src/Umbraco.Core/Models/ContentEditing/PropertyTypeValidation.cs b/src/Umbraco.Core/Models/ContentEditing/PropertyTypeValidation.cs
index 7c35fd156a..5db1ab8139 100644
--- a/src/Umbraco.Core/Models/ContentEditing/PropertyTypeValidation.cs
+++ b/src/Umbraco.Core/Models/ContentEditing/PropertyTypeValidation.cs
@@ -9,7 +9,7 @@ namespace Umbraco.Cms.Core.Models.ContentEditing
     public class PropertyTypeValidation
     {
         [DataMember(Name = "mandatory")]
-        public bool? Mandatory { get; set; }
+        public bool Mandatory { get; set; }
 
         [DataMember(Name = "mandatoryMessage")]
         public string? MandatoryMessage { get; set; }
diff --git a/src/Umbraco.Core/Models/IPropertyType.cs b/src/Umbraco.Core/Models/IPropertyType.cs
index 2e70c64cd9..be7eb5708e 100644
--- a/src/Umbraco.Core/Models/IPropertyType.cs
+++ b/src/Umbraco.Core/Models/IPropertyType.cs
@@ -46,7 +46,7 @@ namespace Umbraco.Cms.Core.Models
         /// <summary>
         /// Gets of sets a value indicating whether a value for this property type is required.
         /// </summary>
-        bool? Mandatory { get; set; }
+        bool Mandatory { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether the label of this property type should be displayed on top.
diff --git a/src/Umbraco.Core/Models/Mapping/ContentPropertyDisplayMapper.cs b/src/Umbraco.Core/Models/Mapping/ContentPropertyDisplayMapper.cs
index 90a608302c..8064925305 100644
--- a/src/Umbraco.Core/Models/Mapping/ContentPropertyDisplayMapper.cs
+++ b/src/Umbraco.Core/Models/Mapping/ContentPropertyDisplayMapper.cs
@@ -48,7 +48,7 @@ namespace Umbraco.Cms.Core.Models.Mapping
             dest.LabelOnTop = originalProp.PropertyType?.LabelOnTop;
 
             //add the validation information
-            dest.Validation.Mandatory = originalProp.PropertyType?.Mandatory;
+            dest.Validation.Mandatory = originalProp.PropertyType?.Mandatory ?? false;
             dest.Validation.MandatoryMessage = originalProp.PropertyType?.MandatoryMessage;
             dest.Validation.Pattern = originalProp.PropertyType?.ValidationRegExp;
             dest.Validation.PatternMessage = originalProp.PropertyType?.ValidationRegExpMessage;
diff --git a/src/Umbraco.Core/Models/Mapping/ContentTypeMapDefinition.cs b/src/Umbraco.Core/Models/Mapping/ContentTypeMapDefinition.cs
index f150523e69..0ded9ad81d 100644
--- a/src/Umbraco.Core/Models/Mapping/ContentTypeMapDefinition.cs
+++ b/src/Umbraco.Core/Models/Mapping/ContentTypeMapDefinition.cs
@@ -317,7 +317,7 @@ namespace Umbraco.Cms.Core.Models.Mapping
             target.Name = source.Label;
             target.DataTypeId = source.DataTypeId;
             target.DataTypeKey = source.DataTypeKey;
-            target.Mandatory = source.Validation?.Mandatory;
+            target.Mandatory = source.Validation?.Mandatory ?? false;
             target.MandatoryMessage = source.Validation?.MandatoryMessage;
             target.ValidationRegExp = source.Validation?.Pattern;
             target.ValidationRegExpMessage = source.Validation?.PatternMessage;
diff --git a/src/Umbraco.Core/Models/PropertyType.cs b/src/Umbraco.Core/Models/PropertyType.cs
index 7db1d0d2b3..12fe07f1c8 100644
--- a/src/Umbraco.Core/Models/PropertyType.cs
+++ b/src/Umbraco.Core/Models/PropertyType.cs
@@ -25,7 +25,7 @@ namespace Umbraco.Cms.Core.Models
         private Lazy<int>? _propertyGroupId;
         private string _propertyEditorAlias;
         private ValueStorageType _valueStorageType;
-        private bool? _mandatory;
+        private bool _mandatory;
         private string? _mandatoryMessage;
         private int _sortOrder;
         private string? _validationRegExp;
@@ -178,7 +178,7 @@ namespace Umbraco.Cms.Core.Models
 
         /// <inheritdoc />
         [DataMember]
-        public bool? Mandatory
+        public bool Mandatory
         {
             get => _mandatory;
             set => SetPropertyValueAndDetectChanges(value, ref _mandatory, nameof(Mandatory));
diff --git a/src/Umbraco.Core/Services/PropertyValidationService.cs b/src/Umbraco.Core/Services/PropertyValidationService.cs
index 093e765948..7aea02ca57 100644
--- a/src/Umbraco.Core/Services/PropertyValidationService.cs
+++ b/src/Umbraco.Core/Services/PropertyValidationService.cs
@@ -40,7 +40,7 @@ namespace Umbraco.Cms.Core.Services
             var editor = _propertyEditors[propertyType.PropertyEditorAlias];
             if (editor == null) throw new InvalidOperationException("No property editor found by alias " + propertyType.PropertyEditorAlias);
 
-            return ValidatePropertyValue(editor, dataType, postedValue, propertyType.Mandatory ?? false, propertyType.ValidationRegExp, propertyType.MandatoryMessage, propertyType.ValidationRegExpMessage);
+            return ValidatePropertyValue(editor, dataType, postedValue, propertyType.Mandatory, propertyType.ValidationRegExp, propertyType.MandatoryMessage, propertyType.ValidationRegExpMessage);
         }
 
         /// <inheritdoc />
@@ -192,7 +192,7 @@ namespace Umbraco.Cms.Core.Services
             }
             var configuration = _dataTypeService.GetDataType(propertyType.DataTypeId).Configuration;
             var valueEditor = editor.GetValueEditor(configuration);
-            return !valueEditor.Validate(value, propertyType.Mandatory ?? false, propertyType.ValidationRegExp).Any();
+            return !valueEditor.Validate(value, propertyType.Mandatory, propertyType.ValidationRegExp).Any();
         }
     }
 }
diff --git a/src/Umbraco.Infrastructure/Persistence/Factories/PropertyGroupFactory.cs b/src/Umbraco.Infrastructure/Persistence/Factories/PropertyGroupFactory.cs
index 2e73ff037c..10b6aadea3 100644
--- a/src/Umbraco.Infrastructure/Persistence/Factories/PropertyGroupFactory.cs
+++ b/src/Umbraco.Infrastructure/Persistence/Factories/PropertyGroupFactory.cs
@@ -131,7 +131,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence.Factories
                 ContentTypeId = contentTypeId,
                 DataTypeId = propertyType.DataTypeId,
                 Description = propertyType.Description,
-                Mandatory = propertyType.Mandatory ?? false,
+                Mandatory = propertyType.Mandatory,
                 MandatoryMessage = propertyType.MandatoryMessage,
                 Name = propertyType.Name,
                 SortOrder = propertyType.SortOrder,