This paper presents the results of interviews conducted as part of the DYNASOS project. The objective was to collect challenges related to the design, implementation and management of system-of-systems (SoS) in the context of climate adaptation and greening of smart cities. 23 individuals from cities, academia, and industry were interviewed between March and May 2022 and 57 distinct challenges were collected and analyzed. Our results show that while technical issues (such as interoperability or data acquisition) persist, non-technical issues are the main obstacles. Difficulties in information sharing, effective communication, and synchronization between different actors are the most important challenges.