Object Storage Service (OSS) cannot generate a temporary URL for an object without verifying the creation time of the object. When a temporary URL is generated, the creation time of the object is verified by default to ensure the validity of the URL. The time when the generated temporary URL takes effect must be greater than or equal to the creation time of the object. Otherwise, the URL is invalid. Therefore, if you want to generate a temporary URL for the object, make sure that the expiration time of the URL is greater than or equal to the creation time of the object. For more information, see Add signatures to URLs.