Komarov was selected to command the Soyuz 1, in 1967, with Yuri Gagarin as his backup cosmonaut. The cosmonauts knew that the spacecraft had major safety problems, but Komarov stated that if he were to refuse to fly, Gagarin would be forced to go instead. Komarov chose to fly to protect Gagarin, and insisted before the flight that his funeral be open-casket so that the Soviet leadership could see what they had done. During the preparations for the spaceflight, both cosmonauts were working twelve- to fourteen-hour days. On orbital insertion, the solar panels of the Soyuz module failed to fully deploy thereby preventing the craft from being fully powered and obscuring some of the navigation equipment. Komarov reported: "Conditions are poor. The cabin parameters are normal, but the left solar panel didn't deploy. The electrical bus is at only 13 to 14 amperes. The HF (high frequency) communications are not working. I cannot orient the spacecraft to the sun. I tried orienting the spacecraft manually using the DO-1 orientation engines, but the pressure remaining on the DO-1 has gone down to 180." Komarov tried unsuccessfully to orient the Soyuz module for five hours. The craft was transmitting unreliable status information, and lost communications on orbits 13 through 15 due to the failure of the high frequency transmitter that should have maintained radio contact while the craft was out of range of the ultra high frequency (UHF) ground receivers.
When interviewed on 17 May by the newspaper Komsomolskaya Pravda, Yuri Gagarin alluded to the failure of the administration to listen to the concerns about the Soyuz module that the cosmonaut corps had identified, and maintained that Komarov's death should teach the establishment to be more rigorous in its testing and evaluation of "all the mechanisms of the spaceship, even more attentive to all stages of checking and testing, even more vigilant in our encounter with the unknown. He has shown us how dangerous the pathway to space is. His flight and his death will teach us courage." In May 1967, Gagarin and Leonov criticised program head Vasily Mishin's "poor knowledge of the Soyuz spacecraft and the details of its operation, his lack of cooperation in working with the cosmonauts in flight and training activities," and asked Kamanin to cite him in the official crash report.
On 26 April 1967, Komarov was given a state funeral in Moscow, and his ashes were interred in the Kremlin Wall Necropolis at Red Square. The American astronauts requested the Soviet government to allow a representative to attend, but were turned down.