About two hours before the scheduled launch time, on Monday, the North American space agency identified an anomaly in a valve on the Atlas V rocket, announced the rocket's manufacturer, the ULA group.
"NASA's priority is safety", reacted the director of the North American space agency, Bill Nelson. Take-off will take place when everything is ready, he wrote on the social network X (formerly Twitter).
A new take-off attempt could happen today, or on Friday or Saturday, but no new date has yet been announced.
Boeing is investing heavily in this latest test mission, which should allow it to join the very small club of spacecraft that transport astronauts.
The aerospace giant must demonstrate that the vehicle is safe before it can begin regular missions to the ISS, four years behind SpaceX.
SpaceX's Dragon capsule joined this list in 2020, succeeding the legendary Mercury, Gemini, Apollo and space shuttle programs.
After the shuttle program ended in 2011, NASA astronauts had to travel aboard the Russian Soyuz spacecraft.
To put an end to this dependence, in 2014, the North American space agency signed contracts worth 4.2 billion dollars (3.9 billion euros) with Boeing and 2.6 billion dollars ( 2.42 billion euros) with SpaceX for the development of new spacecraft.
Once Starliner is operational, NASA hopes to alternate between SpaceX and Boeing flights to take astronauts to the ISS.
After the deactivation of the ISS in 2030, the two ships will be able to be used to transport people to future private space stations, which several North American companies are already planning to build.