In case you weren't aware, the FCC took down the ULS site for upgrades and it was expected to be offline for the extended labor day weekend, but, since this is the federal government we're talking about, it turned out about as well as you would expect.
From the ARRL:
“Over Labor Day weekend, a dedicated FCC team worked day and night to complete major IT upgrades,” the FCC’s Chief Information Officer David A. Bray, said in a statement. “This work included physically moving more than 200 different legacy servers out of FCC's headquarters to a commercial service provider.” This move — a cost-saving measure, Bray explained — ran into trouble when it was determined that additional cabling was needed to complete the transition. “Unfortunately, this delayed completion of all of the system upgrades — even with the FCC team working around the clock throughout the holiday weekend,” Bray explained.For now, attempts to log in to the ULS to look up callsigns (or apply for a vanity callsign for free!) is met with "page cannot be displayed" errors or a continuous "loading" action which will eventually time out.
It should be back online today, but I'm not holding my breath for it.
Only time will tell.