diff --git a/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithydotnet/ServiceCodegen.java b/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithydotnet/ServiceCodegen.java
index 7f0986b93..d3ad8e3a8 100644
--- a/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithydotnet/ServiceCodegen.java
+++ b/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithydotnet/ServiceCodegen.java
@@ -91,9 +91,11 @@ public Map<Path, TokenTree> generate() {
     final Path collectionOfErrorsPath = Path.of("CollectionOfErrors.cs");
     final TokenTree collectionOfErrorsPathCode =
       generateCollectionExceptionClass();
+    final TokenTree genericImport = TokenTree.of("using System.Collections.Generic;");
+
     codeByPath.put(
       collectionOfErrorsPath,
-      collectionOfErrorsPathCode.prepend(prelude)
+      collectionOfErrorsPathCode.prepend(prelude).prepend(genericImport)
     );
 
     // Opaque exception class
@@ -329,9 +331,17 @@ public TokenTree generateCollectionExceptionClass() {
         """
         public class CollectionOfErrors : Exception {
           public readonly System.Collections.Generic.List<Exception> list;
-          public CollectionOfErrors(System.Collections.Generic.List<Exception> list, string message) : base(message) { this.list = list; }
+          public CollectionOfErrors(System.Collections.Generic.List<Exception> list, string message) : base(message + $"\\n List: \\n{ListAsString(list)}") { this.list = list; }
           public CollectionOfErrors(string message) : base(message) { this.list = new System.Collections.Generic.List<Exception>(); }
           public CollectionOfErrors() : base("CollectionOfErrors") { this.list = new System.Collections.Generic.List<Exception>(); }
+          private static string ListAsString(List<Exception> list)
+          {
+            if (list.Count < 1) return "";
+            string [] msgArr = new string [list.Count];
+            for (int i = 0; i < list.Count; i++)
+              msgArr[i] = $"{list[i].GetType().Name} :: {list[i].Message}";
+            return String.Join("\\n\\t", msgArr);
+          }
         }
         """
       )