Space Exploration Technologies Corp. (SpaceX) has again delayed the launch of its next orbital demonstration mission because of problems with the software that will guide its cargo-carrying Dragon capsule into close proximity with the international space station (ISS).

The mission, which has been delayed on account of flight software before, was to have launched May 7. SpaceX spokeswoman Kirstin Grantham said the Hawthorne, Calif., company has yet to set a new date. An internal NASA manifest now lists SpaceX’s launch date as “to-be-determined.” Until the evening of May 3, the same manifest had SpaceX launching “no earlier than May 10.” In preparation for the launch, SpaceX briefly test fired the Falcon 9 in an April 30 hold-down test at Cape Canaveral Air Force Station, Fla. The two-second hot-fire test took place at the Cape’s Space Launch Complex 40. The liquid-fueled engines were ignited at 4:15 p.m. EDT, about an hour later than scheduled.

The countdown for an earlier attempt was halted around 3 p.m. when the “flight computer aborted [the] rocket hold down firing,” Elon Musk, SpaceX’s founder and chief executive, said via Twitter.

SpaceX holds a $1.6 billion contract to fly supplies to the ISS for NASA. Before it can begin those deliveries, the company must complete a demonstration flight in which Dragon approaches and then berths with the station before returning to Earth.