diff --git a/api/src/chat/schemas/types/message.ts b/api/src/chat/schemas/types/message.ts
index 67e3dc0b..f7b370dc 100644
--- a/api/src/chat/schemas/types/message.ts
+++ b/api/src/chat/schemas/types/message.ts
@@ -348,17 +348,17 @@ const quickReplySchema = z
     }
   });
 
-// Attachment Message Schema
-export const objectSchema = z.object({
+// BlockMessage Schema
+export const blockMessageObjectSchema = z.object({
   text: z.string().max(1000).optional(),
   attachment: z
     .object({
       type: z.nativeEnum(FileType),
       payload: z
-        .object({
-          url: z.string().url().optional(),
-          id: z.string().nullable().optional(),
-        })
+        .union([
+          z.object({ url: z.string().url() }),
+          z.object({ id: z.string().nullable() }),
+        ])
         .optional(),
     })
     .optional(),
diff --git a/api/src/chat/validation-rules/is-message.ts b/api/src/chat/validation-rules/is-message.ts
index 057c71cb..5ab9c705 100644
--- a/api/src/chat/validation-rules/is-message.ts
+++ b/api/src/chat/validation-rules/is-message.ts
@@ -15,8 +15,8 @@ import {
 
 import {
   BlockMessage,
+  blockMessageObjectSchema,
   messageRegexSchema,
-  objectSchema,
   textSchema,
 } from '../schemas/types/message';
 
@@ -39,7 +39,7 @@ export function isValidMessage(msg: any) {
     if ('plugin' in msg) {
       return true;
     }
-    const result = objectSchema.safeParse(msg);
+    const result = blockMessageObjectSchema.safeParse(msg);
     if (!result.success) {
       console.error('Block Model: Object validation failed!', result.error);
     }