"At the end, we just ran out of time," NFL executive vice president Eric Grubman said Monday.
Four hundred people were forced to give up their seats for the Green Bay Packers' 31-25 victory over the Pittsburgh Steelers on Sunday night and instead had to watch the game on monitors or use standing-room platforms in corners of Cowboys Stadium.
Another 850 fans were moved from their seats in the temporary sections to other seats.
"It was obviously a failure on our behalf, and we have to take responsibility for that," NFL Commissioner Roger Goodell said Monday at a news conference in Dallas. "We had, obviously, a lot of challenges this week. There were a lot of things we were trying to deal with. But there's no excuses. When you put on an event like this, you know you're going to have those sorts of challenges."
Sunday's temporary seats filled open platforms that are usually standing-room only "party pass" areas for Cowboys games.
Grubman said there "was no vertical structural issue that we were aware of from the police department," but that issues arose with the "final installation of railings, of tightening risers, steps, things of that nature -- and that's what did not get completed at the end."
The league, Grubman said, "felt in the middle of the week that it was going to be a problem. We did not feel until the game day that we had an issue where ... there was a distinct possibility that we wouldn't be able to accommodate fans."
Grubman said final work on the temporary sections was done Sunday afternoon.
In the coming weeks, the NFL will review what happened to figure out what went wrong.
Asked whether Cowboys owner Jerry Jones or local organizers were at fault for the seating issues, Goodell said: "No. We put on this event. This is the responsibility of the NFL."
However, Jones later issued a statement in which he accepted some of the blame and apologized to the impacted fans.
A rare winter storm swept across the area Tuesday, ripping holes in tents on stadium property and hampering travel and celebrations across the region. On Friday, six people at the stadium were injured by melting snow falling from the stadium roof.
"I don't think the weather had any significant contribution to the seating issue," Grubman said.
Goodell said local organizers "did an outstanding job. It was a great event. And I'm sure that they'll be seeking another Super Bowl, and I'm sure the ownership will look at that very seriously."
The Associated Press contributed to this report.