The paper presents the results of an exploratory study of the way digital transformation processes can involve challenges for the security of electricity supply. The case for the study was the development of digital substations in a European electricity grid operator. By means of a sociotechnical approach, we studied digitalization as a process, focusing on transition risks related to the process itself. Six categories of challenges are described: 1) The role of risk assessment and risk management in procurement processes, 2) issues related to language, culture and competence, 3) the management of emergencies and crisis situations, 4) technological aspects of redundancy and oversight, 5) formal organization and responsibility, and 6) changes in regulation, regulatory roles and threat landscape. Common themes cutting across the six categories are discussed and the paper is concluded with a delineation of strategies that can serve to mitigate the risks involved.