Power electronics converters (PECs) are responsible for efficiently converting electrical energy between power generators, storage systems and power consumers/loads. The PECs are subjected to complicated power loading factors throughout their operations and, thus, are proven to have issues regarding lifetime. Therefore, according to the original equipment manufacturers and suppliers, the reliability of the PECs is a key priority in order to be widely used and accepted in the industries. In this context, this review article aims to provide a comprehensive overview of reliability assessment strategies and testing protocols for ensuring the lifetime requirements of PECs. In addition, the paper conducts a thorough investigation of various strategies that are employed to enhance reliability during the design and useful life phase, including the analysis of different types of failure mechanisms, identification of factors contributing to failures, and assessment of techniques for estimating and regulating junction temperatures to prolong the lifetime of the system under real-life operating conditions. Furthermore, the article highlights the challenges encountered in monitoring and predicting component degradation and outlines the crucial steps for conducting a functional safety analysis. Particular emphasis is provided on summarizing the different accelerated aging tests for power electronics converters used in automotive applications, as these tests have yet to be fully covered in previous literature. This study provides an overview and guidelines for understanding the reliability of PECs and identifying potential areas for future research. Finally, the paper concludes most of the ongoing research and innovations in this area and provides insights into the future trends and challenges in enhancing the reliability of power electronics converters.