diff --git a/src/application/JsonFiles.ts b/src/application/JsonFiles.ts
index 583eb0d47b..f0d711e954 100644
--- a/src/application/JsonFiles.ts
+++ b/src/application/JsonFiles.ts
@@ -193,7 +193,9 @@ const decodedJsonFileResult = <Value>(
           decoded.error.issues[0]?.message ?? decoded.error.message,
         ),
       path,
-      userMessage: decoded.error.userMessage,
+      ...(decoded.error.userMessage === undefined
+        ? {}
+        : { userMessage: decoded.error.userMessage }),
       contentIssues: decoded.error.issues,
     }),
   );
diff --git a/src/application/JsonInputFile.ts b/src/application/JsonInputFile.ts
index 41fc919179..3a31333078 100644
--- a/src/application/JsonInputFile.ts
+++ b/src/application/JsonInputFile.ts
@@ -763,7 +763,9 @@ const readNativeJson = async (
     : err(
         invalidJson(operation, parsed.error, {
           cause: parsed.cause,
-          userMessage: parsed.userMessage,
+          ...(parsed.userMessage === undefined
+            ? {}
+            : { userMessage: parsed.userMessage }),
         }),
       );
 };