The ground stop was lifted around 9:20 a.m. for United’s regional carriers. Other issue occurred: United passengers without a hard copy of their boarding pass were not being allowed to check in at Bradley International Airport in Windsor Locks, north of Hartford, and in other airports. The computer problem was forcing United to hand write tickets for passengers at multiple airports. The Federal Aviation Administration said the situation was triggered by “automation issues.” It was not immediately clear what caused the issue. It is the second time in two months that the Chicago carrier has been hit by major technical issues, after a big incident in 2012. Several passengers took to Twitter to express frustration on the issue. Several images showed flight information screens that had gone blank.