Theoretically grounded in Vygotsky's sociocultural theory of mind, Dynamic Assessment (DA) provides researchers with the opportunity to investigate different aspects of learners' developmental trajectory, including the ways they overcome their errors. As a qualitative inquiry into the nature of errors reflecting learners' development in academic writing and the ways they are treated, this study examined the role of face-to-face (FTF) and Computer-Mediated (CM) contexts on the ways Iranian EFL learners dealt with their main developmental errors. In this study, the nature of developmental errors emerged out of the analysis of a writing corpus of four learners participating in a two-month DA based academic writing course. The learners' high-frequency errors were examined through the microgentic development method, which allows for investigating the moment to moment changes in learners' performance, to reveal the ways they were addressed in FTF and CM contexts of DA. The results highlighted the different effects of FTF and CM contexts on learners' pace, depth and permanency of development through not only employing different mediation forms but also encouraging the usage of different mediational tools. The findings indicated that while FTF mediation led to an inclination toward collaborative writing, CM mediation increased learners' engagement with their written texts by focusing more on difficult items and transferring development to other tasks and situations which, in turn, illustrates their progression towards self-regulation. The findings of the study shed light on the potentials of DA in guiding learners' struggle to overcome their academic writing developmental errors in both CM and FTF contexts.