The recent pandemic has forced education to undergo a massive metamorphosis in terms of testing and assessment. The education to not be disbanded and disrupted, online platforms for ensuing it was regarded as the last resort. Instructors either online or face to face are bound to go with providing feedback and assessment. As with the pandemic around, a wide range of platforms were gaining popularity in language teachers. Currently, a good number of platforms are tasked with assessment issues. Putting instructors` teachers’ assessment literacy and their tech-savvy characters, language teachers are struggling with designing and administering the online assessment. Despite this need and the urgency of the matter, not more than a few studies have been conducted on online assessment challenges. In the place of addressing this need, the current qualitative research by examining 56 EFL instructors of Preparatory Language Schools tries to enrich the literature of the field. The study has tried to shed light on the challenge perception of instructors and the likely solutions in Turkish Preparatory Language Schools. In this regard, 56 instructors with MA and Ph.D. degrees have been selected to conduct the study. The data was collected by an open-ended questionnaire and resolute sampling and it got analysed by MAXQDA 2020. Cases like personal and characteristic differences, ethics, infrastructure, and policy power, mediating artefacts, teacher and student assessment and feedback literacy, and teacher and student technology literacy were the main challenges identified by applying online assessment. The findings obtained from the research can help better professional development practices, policy-making, and teacher training programs. Thanks to the study a sample and road map could e designed to have a better, proficient, and effective online assessment.