SpaceX scrubbed a planned launch on Saturday from Kennedy Space Center, citing a “slightly odd” thrust control problem and delaying the return to service for a historic launchpad at the Florida spaceport.

“All systems go, except the movement trace of an upper stage engine steering hydraulic piston was slightly odd,” CEO Elon Musk said on Twitter. “If this is the only issue, flight would be fine, but need to make sure that it isn’t symptomatic of a more significant upstream root cause.”

Btw, 99% likely to be fine (closed loop TVC wd overcome error), but that 1% chance isn't worth rolling the dice. Better to wait a day. — Elon Musk (@elonmusk) February 18, 2017

SpaceX halted the countdown with just 13 seconds remaining, though engineers had noticed the problem with the second-stage thrust control several minutes earlier. With just a single second to get the Falcon rocket airborne, flight controllers could not resolve the issue in time.

“Hold, hold, hold!” a launch controller urged over the radio loops, to the disappointment of thousands of guests who jammed the space center to witness the comeback of 39A, last used in 2011 for the last space shuttle flight. “Standing down to take a closer look at positioning of the second stage engine nozzle,” SpaceX said on Twitter.

The next launch attempt, provided everything can be fixed quickly, is scheduled for Sunday morning.

This will be SpaceX’s first Florida launch since a rocket explosion last autumn. In September, an accident during prelaunch testing caused a gigantic explosion, destroying a Falcon 9 rocket and its satellite payload. In January, SpaceX successfully launched a rocket from a California pad and landed it on a barge in the Pacific.