This glitch has so far only affected domestic United flights in the U.S., reports Reuters. International flights and international-bound flights leaving from the U.S. are not affected.
A ground stop is in place for domestic flights due to an IT issue. We're working on a resolution. We apologize for the inconvenience.— United (@united) January 23, 2017
UPDATE: The ground stop has been lifted. We're working to get flights on their way. We apologize for the inconvenience to our customers.— United (@united) January 23, 2017
UPDATE: Additional delays are expected as we work to get flights out this evening. A travel waiver is in place: https://t.co/pyXEh3LCwX.— United (@united) January 23, 2017