3 files changed, 13 insertions, 2 deletions

diff --git a/src/WixToolset.Data/ErrorMessages.cs b/src/WixToolset.Data/ErrorMessages.cs
index cb8d5f8f..d0736628 100644
--- a/src/WixToolset.Data/ErrorMessages.cs
+++ b/src/WixToolset.Data/ErrorMessages.cs
@@ -2279,6 +2279,11 @@ namespace WixToolset.Data
             return Message(null, Ids.IntermediatesMustBeResolved, "Intermediates being bound must have been resolved. This intermediate was not resolved: {0}", invalidIntermediate);
         }
 
+        public static Message UnknownSymbolType(string symbolName)
+        {
+            return Message(null, Ids.UnknownSymbolType, "Could not deserialize symbol of type type '{0}' because it is not a standard symbol type or one provided by a loaded extension.", symbolName);
+        }
+
         private static Message Message(SourceLineNumber sourceLineNumber, Ids id, string format, params object[] args)
         {
             return new Message(sourceLineNumber, MessageLevel.Error, (int)id, format, args);
@@ -2680,6 +2685,7 @@ namespace WixToolset.Data
             IntermediatesMustBeResolved = 396,
             MissingBundleSearch = 397,
             CircularSearchReference = 398,
+            UnknownSymbolType = 399,
         }
     }
 }
diff --git a/src/WixToolset.Data/IntermediateTuple.cs b/src/WixToolset.Data/IntermediateTuple.cs
index 8a5858ee..9146b2be 100644
--- a/src/WixToolset.Data/IntermediateTuple.cs
+++ b/src/WixToolset.Data/IntermediateTuple.cs
@@ -165,7 +165,12 @@ namespace WixToolset.Data
             var id = (idJson == null) ? null : Identifier.Deserialize(idJson);
             var sourceLineNumbers = (sourceLineNumbersJson == null) ? null : SourceLineNumber.Deserialize(sourceLineNumbersJson);
 
-            creator.TryGetTupleDefinitionByName(definitionName, out var definition); // TODO: this isn't sufficient.
+            // TODO: this isn't sufficient.
+            if (!creator.TryGetTupleDefinitionByName(definitionName, out var definition))
+            {
+                throw new WixException(ErrorMessages.UnknownSymbolType(definitionName));
+            }
+
             var tuple = definition.CreateTuple(sourceLineNumbers, id);
 
             for (var i = 0; i < fieldsJson.Count && i < tuple.Fields.Length; ++i)
diff --git a/src/WixToolset.Data/WarningMessages.cs b/src/WixToolset.Data/WarningMessages.cs
index 55bf2c2c..b31f5aaf 100644
--- a/src/WixToolset.Data/WarningMessages.cs
+++ b/src/WixToolset.Data/WarningMessages.cs
@@ -504,7 +504,7 @@ namespace WixToolset.Data
 
         public static Message RequiresMsi500forArmPackage(SourceLineNumber sourceLineNumbers)
         {
-            return Message(sourceLineNumbers, Ids.RequiresMsi500forArmPackage, "Package/@InstallerVersion must be 500 or greater for an Arm package. The value will be changed to 500. Please specify a value of 500 or greater in order to eliminate this warning.");
+            return Message(sourceLineNumbers, Ids.RequiresMsi500forArmPackage, "Package/@InstallerVersion must be 500 or greater for an ARM or ARM64 package. The value will be changed to 500. Please specify a value of 500 or greater in order to eliminate this warning.");
         }
 
         public static Message ReservedAttribute(SourceLineNumber sourceLineNumbers, string elementName, string attributeName)