NestJS Debugging Guide

This guide provides a systematic approach to debugging NestJS applications. Use the four-phase methodology below to efficiently identify and resolve issues.

Common Error Patterns

1. Dependency Resolution Errors

Error Message:

Nest can't resolve dependencies of the <ProviderName> (?). Please make sure that the argument <DependencyName> at index [0] is available in the <ModuleName> context.

Common Causes:

• Provider not added to module's providers array
• Missing @Injectable() decorator on service class
• Incorrect import/export between modules
• Typo in injection token name
• Missing forRoot()/forRootAsync() configuration