PITTSBURGH, Pa. (AP) – Carnegie Mellon University is apologizing after mistakenly telling about 800 applicants they got into a graduate computer science program.

The prestigious Pittsburgh university says it erroneously emailed acceptance letters to the applicants, only to tell them hours later that they didn’t get in.

Carnegie Mellon said Tuesday that the emails resulted from “serious mistakes” in its process for generating acceptance letters.

One applicant said he learned of the retraction after going out to dinner with his family to celebrate.

Ben Leibowitz, of Stamford, Connecticut, says Carnegie Mellon’s follow-up email said its offer was an error and that there wasn’t a place for him at the school this year. Leibowitz says he’s left to clean up the mess and explain what happened to his relatives.

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