During launch to Earth orbit, the third stage (Blok I) engine cut off prematurely at T+524.6 seconds because of an excessive propellant consumption rate via the gas generator. The spacecraft never reached Earth orbit.
The goal of the mission was to test communications systems in support of the N1-L3 human lunar landing program.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.