The evolution of software libraries is a process that requires a joint effort of two groups of developers: the library developers who prepare the release and client developers who need to update their applications to the new versions. To build better tools that support both library and client developers throughout the evolution, we need to understand what problems they face and how they react to those problems. In this paper, we present the result of two surveys: one for library developers and one for client developers. Our surveys involved developers from two industrial companies and an open-source community. We assess (1) how they perceive the impact of library evolution and (2) what is the support that library developers can provide to their clients. By approaching those questions from the perspectives of library and client developers, we try to assess how challenging library update is for each of those groups and how motivated they are to overcome those challenges.