In addition to UA127 mentioned above
UA34 KIX-SFO 772 cancelled due to an unexpected operational issue. Replacement flight UA3045 was scheduled with the same departure time.
UA216 EWR-PDL 38M cancelled due to software outage. Return UA217 PDL-EWR on 7/21 cancelled as a result.
UA980 ORD-DUB 752 cancelled due to maintenance.
UA981 DUB-ORD 752 cancelled due to maintenance after a 2 hr 10 min delay.