ERROR [ExceptionHandler] Cannot read property '__guards__' of undefined in NestJs

Question

I'm working on implementing a simple authentication in a Nest project.

When I add

@UseGuards(AuthGuard('local'))

to my controller I have the following Error :

ERROR [ExceptionHandler] Cannot read property '__guards__' of undefined
 at /home/cedric/Bureau/programmation/project_bank/project/node_modules/@nestjs/core/scanner.js:147:152

I followed all the Nest official documentation to do this.

My controller is

  @UseGuards(AuthGuard('local'))
  @Post('login')
  async login(@Request() req) {
    console.log(req.body.username);
    return req.body.username;
  }

and my auth.guard.ts

@Injectable()
export class LocalAuthGuard extends AuthGuard('local') {}

Answer 1

I'd say this is a dependency version mismatch issue.

You need to ensure that @nestjs/platform-express, @nestjs/core and @nestjs/common are in the same version (I believe that only the minor slice matters).

Answer 2

It really was a dependency version mismatch.

I followed this procedure to update my project :

1. Install ncu from the npm-check-updates library:

sudo npm install -g npm-check-updates

2. Run ncu in the project folder :

ncu

3. Update your dependencies:

ncu -u

4. Finally, install the updates

npm install