This study explores international students' perceptions of the transition to the online learning environment while they were studying on an Erasmus+ Study Mobility Programme at host universities in Europe during the COVID-19 pandemic in spring 2020. Applying the theoretical framework based on the affective, behavioural and cognitive aspects of adaptation in the case of international students, this study reveals what adaptive responses and decisions sojourners made, and how their study experience and learning capabilities were challenged by the restrictive measures introduced at host universities due to the state of emergency declared in the host countries. Fourteen semi-structured interviews with both incoming and outgoing international students were conducted. Results reveal that studying online with reduced social interaction was a real challenge to Erasmus students. They were lacking cultural knowledge of the destination country as well as the insights typically arising from face-to-face teaching and social interactions. However, findings also expose students' satisfaction with their academic accomplishments. In this regard, specific proposals are made for universities that consider virtual mobility programmes for international students in the future.