The Internet of Vehicles (IoV) is a fast developing field that seeks to use cutting-edge technologies to enhance the sustainability, efficiency, and safety of transportation networks. The IoV can gain greatly from integrating blockchain in terms of security, trust, decentralization, smart contracts, and data management. This paper presents the weakness of a blockchain based lightweight authentication and key agreement scheme for internet of vehicles(BLAIV) proposed by Zheng et al. [1]. By performing thorough security analysis we have observed that the BLAIV scheme is vulnerable to various security attacks. The main cause for the security attacks is the BLAIV scheme stores the security parameters in the Onboard unit(OBU) of vehicle, due to which the BLAIV scheme is vulnerable to various attacks like vehicle or OBU capture attacks, session key computation attacks, and impersonation attacks. The paper also suggests possible changes to improve the BLAIV scheme.