Unlocking the potential of zeolite membranes consists in overcoming the persistent challenge of defects formation, a barrier against their application at industrial scale. Understanding the mechanisms underlying defects formation is mandatory for achieving precise control and optimization of membrane performance. This paper offers a comprehensive exploration of the diverse defects of zeolite membranes, investigating the factors responsible for their occurrence during membrane preparation such as crystallization kinetics, seeding techniques and template removal. Furthermore, a variety of characterization techniques used to identify defects are examined, highlighting their features and drawbacks. This review also explores the current strategies to heal defects, including post-treatment methods and preparation optimization. Through this elucidation, the paper aims to make a progress in addressing the defect issue in zeolite membranes.