June 1 (UPI) — After several delays, test pilots Sunita “Suni” Williams and Barry “Butch” Wilmore scheduled launch of the first crewed mission of the Boeing Starliner spacecraft was scrubbed Saturday afternoon.

A United Launch Alliance Atlas V rocket was set to launch the Starliner into space rom the Space Launch Complex-41 in Florida at 12:25 p.m. EDT. The hold was at 3:56 p.m.

NASA is streaming the launch live on its YouTube channel.

The crew then was to be removed from the spacecraft.

Shortly before the hold, all systems were “go” but an automatic hold was triggered by a flight sequening compter. No details were revealed.

Around 10 a.m., teams found a loss of data from ground valves responsible for replenishing the liquid oxygen and hydrogen to the second, or upper stage, of the Atlas V rocket. The hatch was prevented from closing for about 45 minutes. The countdown resumed after a redunant system was used.

Williams and Wilmore gaved the Starliner its final shakedown run, which includes a week-long stay while docked at the International Space Station.

The test pilots will spend two days traveling to the ISS, where it will dock and remain for about a week while testing the Starliner’s ability to support a crew while in space.

The Starliner will return to Earth with a landing planned in the U.S. desert Southwest.

The Starliner is designed with a service life of 10 launches and landings.

Earlier test launches were delayed for many reasons, including the use of flammable tape in the Starliner capsule, a buzzing noise detected on the launch pad, a defective pressure valve on an upper-stage oxygen tank and a helium leak in the service module.

If the 10-day test flight proceeds successfully, NASA likely will certify the Starliner for use.