Just two months before they were to begin classes, 499 young men and women who had been accepted to the University of California, Irvine, received letters informing them that their acceptances had been rescinded.

The letters that went out starting last week left students scrambling to either appeal the decision or make other plans for the fall.

“This is not a typical year,” Tom Vasich, a spokesman for the university, said in a phone interview on Friday. He said the problem arose because “more students than we expected accepted admission to the university.”

Associated Students of the University of California, Irvine, a student government organization, said in a statement to the school’s enrollment staff on Thursday that the acceptances of some applicants had been rescinded even though they had not made any of the mistakes that would have endangered their admission.