Weather conditions
This version was put forward by Vladimir Aksenov, pilot-cosmonaut, twice Hero of the Soviet Union. According to him, the cause of the tragedy was the increased cloud coverage on the day of the flight. The pilots lost control in difficult meteorological conditions and made a fatal mistake that cost both of them their lives. As a proof for his version Aksenov cites images from the weather balloons.
Pilots' mistake
According to this version, the pilots died after they failed to correctly perform one of the aerobatic maneuvers, which, by the way, was not specified in the mission. This theory was put forward by the retired Air Force Colonel, Eduard Alexandrovich Shersher. He suggested that the pilots decided to perform several sharp turns, "on skill, as entertainment", so to speak. However, due to the unsuitability of this aircraft model to such loads and due to increased cloud coverage, this idea ended in tragedy.
Conspiracy theories
There are also several conspiracy theories that are not seriously considered by anyone.
For example, some suggested that Gagarin's death was a political order in the highest circles of power, which the famous cosmonaut somehow did not please. There was a version, according to which the cosmonaut died a few days before the accident, during the testing of a new spaceship, the development of which was strictly classified. In addition, there were also those who claimed that they saw Gagarin with their own eyes many years after his death. They say that the pilot has deliberately faked his death in order to spend the last years of his life somewhere in the Orenburg forests.