Which type of testing should be done after a release upgrade has occurred?

Regression tests are a type of testing that should be done after a release upgrade has occurred. Regression tests are performed to ensure that the existing functionality of the system is not affected by the changes introduced by the new release. Regression tests help to identify any defects or errors that may have been introduced or uncovered by the release upgrade. Regression tests are part of the quality assurance process and are essential for ensuring the stability and reliability of the system. References = SAP S/4HANA Cloud, Public Edition - All Learning Journeys | SAP Learning -> Implementing SAP S/4HANA Cloud Public Edition -> Unit 5: Quality Assurance -> Lesson: Performing Regression Tests