The cause of the Progress accident was an abnormal separation of the third stage of the launch vehicle and the cargo spacecraft. According to the head of Roscosmos Igor Komarov, this was caused by "depressurization of the oxidizer tank and the third-stage fuel tank."
According to the deputy head of the department, Alexander Ivanov, the energy from the depressurization of the tanks was enough to throw the Progress 40 kilometers above the calculated orbit.
Komarov said that the special commission would determine the exact cause of the emergency situation with the Soyuz-2.1a launch vehicle and the ship by May 22.