How managers frame and make sense of unexpected events in project implementation

•Sensemaking is a social process by which people make sense of events that are bewildering or perplexing in light of unmet expectations.•By adopting a processual longitudinal study, we explore how over time unexpected events trigger sensemaking among project participants and lead them to revise their framing.•Our findings extend the understanding of how actors implementing large projects navigate surprises posed by unexpected events.•We contribute to discussions in project work by exploring how actors’ framing of events evolves in the process of project implementation.