Having witnessed the unprecedented prevalence of online education during the COVID-19 pandemic worldwide, the present research was motivated to explore the challenges facing an EFL teacher throughout an online English course of intermediate level. To this aim, a process-tracing approach (Checkel, 2006) was employed to unravel the causal mechanisms involved in the beginning, middle, and end of the course. The results showed that deficient technological resources caused the greatest challenges throughout the course, especially in the initial and mid-sessions. Also, the two other causal categories, human and content resources, were at their peak at the beginning of the course and were no longer noticeable at the end of the course. The most troublesome challenges the teacher faced were platform limitations, internet connection, and human resources’ unpreparedness for online education. Furthermore, the teacher’s and most students’ technological knowledge, as well as their media literacy, increased by the end of the course, but some students’ rather slow adaptation to the sudden online environment challenged the teacher during the course. Finally, suggestions were made to prevent these challenges or handle them effectively upon occurrence, especially in developing countries, where the required infrastructure for online education is lacking, and the majority of teachers, students, and institutions might not be yet adequately prepared for the online mode of teaching and learning languages.
