Express.js has emerged as a dynamic and versatile framework that stands as a one-stop shop for crafting robust web applications, largely driven by the rise of containerization and microservices architectures. Its popularity owes much to its minimalist approach, allowing developers to swiftly build APIs and web applications with ease. The open-source community of Express.js is a driving force that has propelled it from a simple framework to a comprehensive ecosystem. To debug containerized Express.js applications, it's essential to understand the unique characteristics of the container environment and adapt traditional debugging practices accordingly. Common errors in Express.js on containers include middleware errors, routing errors, container configuration errors, networking errors, and others. Effective debugging tools and techniques can help identify and fix these issues, improving the performance and reliability of the app. Tools like Lumigo provide a visual debugging platform to trace through multiple managed services, helping developers determine the root cause of an issue quickly. Additionally, embracing immutable and stateless design principles in containerized applications ensures efficiency, reliability, and scalability. By familiarizing oneself with these practices and tools, developers can efficiently debug and resolve issues arising with their Express.js applications.