diff --git a/src/Umbraco.Core/Exceptions/InvalidCompositionException.cs b/src/Umbraco.Core/Exceptions/InvalidCompositionException.cs
index 95cd27b2cd..5d2beaa387 100644
--- a/src/Umbraco.Core/Exceptions/InvalidCompositionException.cs
+++ b/src/Umbraco.Core/Exceptions/InvalidCompositionException.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.Serialization;
+using System.Text;
 
 namespace Umbraco.Core.Exceptions
 {
@@ -85,18 +86,28 @@ namespace Umbraco.Core.Exceptions
 
         private static string FormatMessage(string contentTypeAlias, string addedCompositionAlias, string[] propertyTypeAliases, string[] propertyGroupAliases)
         {
-            // TODO Add property group aliases to message
-            return addedCompositionAlias.IsNullOrWhiteSpace()
-                    ? string.Format(
-                        "ContentType with alias '{0}' has an invalid composition " +
-                        "and there was a conflict on the following PropertyTypes: '{1}'. " +
-                        "PropertyTypes must have a unique alias across all Compositions in order to compose a valid ContentType Composition.",
-                        contentTypeAlias, string.Join(", ", propertyTypeAliases))
-                    : string.Format(
-                        "ContentType with alias '{0}' was added as a Composition to ContentType with alias '{1}', " +
-                        "but there was a conflict on the following PropertyTypes: '{2}'. " +
-                        "PropertyTypes must have a unique alias across all Compositions in order to compose a valid ContentType Composition.",
-                        addedCompositionAlias, contentTypeAlias, string.Join(", ", propertyTypeAliases));
+            var sb = new StringBuilder();
+
+            if (addedCompositionAlias.IsNullOrWhiteSpace())
+            {
+                sb.AppendFormat("Content type with alias '{0}' has an invalid composition.", contentTypeAlias);
+            }
+            else
+            {
+                sb.AppendFormat("Content type with alias '{0}' was added as a composition to content type with alias '{1}', but there was a conflict.", addedCompositionAlias, contentTypeAlias);
+            }
+
+            if (propertyTypeAliases.Length > 0)
+            {
+                sb.AppendFormat(" Property types must have a unique alias across all compositions, these aliases are duplicate: {0}.", string.Join(", ", propertyTypeAliases));
+            }
+
+            if (propertyGroupAliases.Length > 0)
+            {
+                sb.AppendFormat(" Property groups with the same alias must also have the same type across all compositions, these aliases have different types: {0}.", string.Join(", ", propertyGroupAliases));
+            }
+
+            return sb.ToString();
         }
 
         /// <summary>
diff --git a/src/Umbraco.Core/Services/Implement/ContentTypeServiceBaseOfTRepositoryTItemTService.cs b/src/Umbraco.Core/Services/Implement/ContentTypeServiceBaseOfTRepositoryTItemTService.cs
index 11142ad96e..385bfec923 100644
--- a/src/Umbraco.Core/Services/Implement/ContentTypeServiceBaseOfTRepositoryTItemTService.cs
+++ b/src/Umbraco.Core/Services/Implement/ContentTypeServiceBaseOfTRepositoryTItemTService.cs
@@ -97,18 +97,22 @@ namespace Umbraco.Core.Services.Implement
                     stack.Push(c);
             }
 
+            var duplicatePropertyTypeAliases = new List<string>();
+            var invalidPropertyGroupAliases = new List<string>();
+
             foreach (var dependency in dependencies)
             {
                 if (dependency.Id == compositionContentType.Id) continue;
                 var contentTypeDependency = allContentTypes.FirstOrDefault(x => x.Alias.Equals(dependency.Alias, StringComparison.InvariantCultureIgnoreCase));
                 if (contentTypeDependency == null) continue;
 
-                var duplicatePropertyTypeAliases = contentTypeDependency.PropertyTypes.Select(x => x.Alias).Intersect(propertyTypeAliases, StringComparer.InvariantCultureIgnoreCase).ToArray();
-                var invalidPropertyGroupAliases = contentTypeDependency.PropertyGroups.Where(x => propertyGroupAliases.TryGetValue(x.Alias, out var type) && type != x.Type).Select(x => x.Alias).ToArray();
+                duplicatePropertyTypeAliases.AddRange(contentTypeDependency.PropertyTypes.Select(x => x.Alias).Intersect(propertyTypeAliases, StringComparer.InvariantCultureIgnoreCase));
+                invalidPropertyGroupAliases.AddRange(contentTypeDependency.PropertyGroups.Where(x => propertyGroupAliases.TryGetValue(x.Alias, out var type) && type != x.Type).Select(x => x.Alias));
+            }
 
-                if (duplicatePropertyTypeAliases.Length == 0 && invalidPropertyGroupAliases.Length == 0) continue;
-
-                throw new InvalidCompositionException(compositionContentType.Alias, null, duplicatePropertyTypeAliases, invalidPropertyGroupAliases);
+            if (duplicatePropertyTypeAliases.Count > 0 || invalidPropertyGroupAliases.Count > 0)
+            {
+                throw new InvalidCompositionException(compositionContentType.Alias, null, duplicatePropertyTypeAliases.Distinct().ToArray(), invalidPropertyGroupAliases.Distinct().ToArray());
             }
         }
 
diff --git a/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs b/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs
index 6ac936961f..0f3df41fc4 100644
--- a/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs
+++ b/src/Umbraco.Web/Editors/ContentTypeControllerBase.cs
@@ -454,10 +454,12 @@ namespace Umbraco.Web.Editors
             var validateAttempt = service.ValidateComposition(composition);
             if (validateAttempt == false)
             {
-                //if it's not successful then we need to return some model state for the property aliases that
-                // are duplicated
-                var invalidPropertyAliases = validateAttempt.Result.Distinct();
-                AddCompositionValidationErrors<TContentTypeSave, TPropertyType>(contentTypeSave, invalidPropertyAliases);
+                // if it's not successful then we need to return some model state for the property type and property group
+                // aliases that are duplicated
+                var duplicatePropertyTypeAliases = validateAttempt.Result.Distinct();
+                var invalidPropertyGroupAliases = (validateAttempt.Exception as InvalidCompositionException)?.PropertyGroupAliases ?? Array.Empty<string>();
+
+                AddCompositionValidationErrors<TContentTypeSave, TPropertyType>(contentTypeSave, duplicatePropertyTypeAliases, invalidPropertyGroupAliases);
 
                 var display = Mapper.Map<TContentTypeDisplay>(composition);
                 //map the 'save' data on top
@@ -472,22 +474,32 @@ namespace Umbraco.Web.Editors
         /// Adds errors to the model state if any invalid aliases are found then throws an error response if there are errors
         /// </summary>
         /// <param name="contentTypeSave"></param>
-        /// <param name="invalidPropertyAliases"></param>
+        /// <param name="duplicatePropertyTypeAliases"></param>
+        /// <param name="invalidPropertyGroupAliases"></param>
         /// <returns></returns>
-        private void AddCompositionValidationErrors<TContentTypeSave, TPropertyType>(TContentTypeSave contentTypeSave, IEnumerable<string> invalidPropertyAliases)
+        private void AddCompositionValidationErrors<TContentTypeSave, TPropertyType>(TContentTypeSave contentTypeSave, IEnumerable<string> duplicatePropertyTypeAliases, IEnumerable<string> invalidPropertyGroupAliases)
             where TContentTypeSave : ContentTypeSave<TPropertyType>
             where TPropertyType : PropertyTypeBasic
         {
-            foreach (var propertyAlias in invalidPropertyAliases)
+            foreach (var propertyTypeAlias in duplicatePropertyTypeAliases)
             {
-                // Find the property relating to these
-                var property = contentTypeSave.Groups.SelectMany(x => x.Properties).Single(x => x.Alias == propertyAlias);
+                // Find the property type relating to these
+                var property = contentTypeSave.Groups.SelectMany(x => x.Properties).Single(x => x.Alias == propertyTypeAlias);
                 var group = contentTypeSave.Groups.Single(x => x.Properties.Contains(property));
                 var propertyIndex = group.Properties.IndexOf(property);
                 var groupIndex = contentTypeSave.Groups.IndexOf(group);
 
                 var key = $"Groups[{groupIndex}].Properties[{propertyIndex}].Alias";
-                ModelState.AddModelError(key, "Duplicate property aliases not allowed between compositions");
+                ModelState.AddModelError(key, "Duplicate property aliases aren't allowed between compositions");
+            }
+
+            foreach (var propertyGroupAlias in invalidPropertyGroupAliases)
+            {
+                // Find the property group relating to these
+                var group = contentTypeSave.Groups.Single(x => x.Alias == propertyGroupAlias);
+                var groupIndex = contentTypeSave.Groups.IndexOf(group);
+                var key = $"Groups[{groupIndex}].Name";
+                ModelState.AddModelError(key, "Different group types aren't allowed between compositions");
             }
         }
 
@@ -519,7 +531,7 @@ namespace Umbraco.Web.Editors
             }
             if (invalidCompositionException != null)
             {
-                AddCompositionValidationErrors<TContentTypeSave, TPropertyType>(contentTypeSave, invalidCompositionException.PropertyTypeAliases);
+                AddCompositionValidationErrors<TContentTypeSave, TPropertyType>(contentTypeSave, invalidCompositionException.PropertyTypeAliases, invalidCompositionException.PropertyGroupAliases);
                 return CreateModelStateValidationException<TContentTypeSave, TContentTypeDisplay>(ctId, contentTypeSave, ct);
             }
             return null;