Internal error issue

I have tested the Dynamic block successfully but when I’m using live version I get error and it goes to fallback:
 

Level:error

Date:15 Feb 2025, 15:42 (UTC +03:30)

Description:Internal error

Type:Dynamic Block

I used the json same as document:

 

@api.route('/new_message', methods=['POST'])
def process_message():
    return {
        "version": "v2",
        "content": {
            "messages": [
            {
                "type": "text",
                "text": "simple text with button",
                "buttons": [
                {
                    "type": "url",
                    "caption": "External link",
                    "url": "https://manychat.com"
                }
                ]
            }
            ]
        }
    }