Organizations increasingly experiment with new interfaces for knowledge sharing to foster innovation. More precisely, a variety of actors from inside and outside the organization who before hardly had any interfaces in their daily work are now expected to share their knowledge. Using data collected in an explorative qualitative study with innovation managers across Europe we explore what types of semantic and pragmatic boundaries exist as barriers to knowledge sharing at newly emerging interfaces. Thereby, distinct open and hidden behavioral patterns have been identified for each type of boundary. This understanding is a precondition for fostering and managing knowledge processes at newly emerging interfaces. Also, it enables practitioners and researchers alike to engage in a more nuanced discussion of these new facets of complexity of knowledge sharing in innovation projects.