In this paper, we analyze two instances of interactional breakdown in linguistically and culturally diverse classrooms in Copenhagen and Helsinki. Our focus is situations where teachers request the use of minority languages from pupils, and pupils react reluctantly and display embarrassment. These situations represent sociolinguistic spaces of upset understood as disruptions of prevailing language ideologies and sociolinguistic regimes. We argue that pupils’ reluctance to comply with teachers’ attempts to include minority languages exemplifies such a disruption, and meta-communicative exchanges represent a window into the language ideologies influencing such situations. We analyze the interactions sequentially through the theoretical lens of enregisterment, linguistic legitimacy, and raciolinguistic microaggressions. The Helsinki data are drawn from a sociolinguistically informed action research project in an elementary school. The Copenhagen data involve lower-secondary-level pupils and consist of observations and recordings collected as part of a long-term ethnographic study. Despite the differences in projects and field sites, we found a striking similarity both in the language ideologies displayed by teachers and in pupils’ reactional patterns. Consequently, we argue that both examples represent the same type of sociolinguistic space of upset characterized by an intrinsic dilemma in Nordic public schools, which are simultaneously expected to secure the continuation of mainstream culture and embrace linguistic diversity.