In a monolithic application, if one part of the service has an error, what happens to the application?

In a monolithic architecture, the application is designed as a single cohesive unit where all components are interdependent. This means that different functionalities are tightly integrated, and they share the same resources and execution context.

When an error occurs in one part of the service, it can cascade through the application due to this tight coupling. For example, if a critical component encounters an unexpected failure or exception that is not properly handled, it can lead to the entire application becoming unresponsive. Since all components are running in the same process, the fault in one can impact the stability of the entire application, leading to a shutdown.

This characteristic is a key limitation of monolithic applications, making fault isolation difficult. In contrast, more modern architectures like microservices are designed to mitigate such risks by isolating failures to individual services, allowing other parts of the application to continue functioning even in the face of errors.