Musk tweeted last night that there was a potential leak issue that might cause a scrub during the launch. They added an automatic check for the problem, and it appears that's what caused the scrub.
Since this is a launch to the ISS, the launch window was tiny- miss it by a second, you've missed it completely.
They'll fix the issue and probably try again tomorrow.
Edit: my mistake, Musk has tweeted that there was another probably-unrelated-maybe-issue, and they called it off just to be safe. Still, provided the minor issue doesn't turn out to be something more major, tune in tomorrow at 9:30 am EST.
Since this is a launch to the ISS, the launch window was tiny- miss it by a second, you've missed it completely.
They'll fix the issue and probably try again tomorrow.
Edit: my mistake, Musk has tweeted that there was another probably-unrelated-maybe-issue, and they called it off just to be safe. Still, provided the minor issue doesn't turn out to be something more major, tune in tomorrow at 9:30 am EST.