Angular Universal - TypeError: Converting circular structure to JSON

Question

I am having a big problem related to Angular Server-Side Rendering (SSR), the usage of Resolvers and HTTP requests. I am building a project in Angular 13, but I decided to implement SSR in order to improve the experience with SEO and redirection in case of a change in the structure of the URL.

I decided to install it through ng add @nguniversal/express-engine as reported in the documentation. Unfortunately, when I start the application with ng run project:serve-ssr all builds correctly, but when I visit the homepage which uses Resolvers with services generated with ng-openapi-gen, the page does not render and I receive the following error.

ERROR TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'XMLHttpRequest'
    |     property 'upload' -> object with constructor 'XMLHttpRequestUpload'
    --- property '_request' closes the circle
    at JSON.stringify (<anonymous>)
    at readableObjectToString (/home/user/project/dist/project/server/main.js:122623:59)
    at resolvePromise (/home/user/project/dist/project/server/main.js:122823:59)
    at resolvePromise (/home/user/project/dist/project/server/main.js:122770:11)
    at /home/user/project/dist/project/server/main.js:122897:11
    at _ZoneDelegate.invokeTask (/home/user/project/dist/project/server/main.js:121862:173)
    at Object.onInvokeTask (/home/user/project/dist/project/server/main.js:205242:33)
    at _ZoneDelegate.invokeTask (/home/user/project/dist/project/server/main.js:121862:56)
    at Zone.runTask (/home/user/project/dist/project/server/main.js:121612:39)
    at drainMicroTaskQueue (/home/user/project/dist/project/server/main.js:122082:25) {
  rejection: HttpErrorResponse {
    headers: HttpHeaders {
      normalizedNames: Map {},
      lazyUpdate: null,
      headers: Map {}
    },
    status: 0,
    statusText: 'Unknown Error',
    url: 'https://localhost:4200/api/v1/chords/',
    ok: false,
    name: 'HttpErrorResponse',
    message: 'Http failure response for https://localhost:4200/api/v1/chords/: 0 Unknown Error',
    error: ProgressEvent {
      type: 'error',
      target: [XMLHttpRequest],
      currentTarget: [XMLHttpRequest],
      lengthComputable: false,
      loaded: 0,
      total: 0
    }
  },
  promise: ZoneAwarePromise [Promise] {
    __zone_symbol__state: 0,
    __zone_symbol__value: HttpErrorResponse {
      headers: [HttpHeaders],
      status: 0,
      statusText: 'Unknown Error',
      url: 'https://localhost:4200/api/v1/chords/',
      ok: false,
      name: 'HttpErrorResponse',
      message: 'Http failure response for https://localhost:4200/api/v1/chords/: 0 Unknown Error',
      error: [ProgressEvent]
    }
  },
  zone: Zone {
    _parent: Zone {
      _parent: null,
      _name: '<root>',
      _properties: {},
      _zoneDelegate: [_ZoneDelegate]
    },
    _name: 'angular',
    _properties: { isAngularZone: true },
    _zoneDelegate: _ZoneDelegate {
      _taskCounts: [Object],
      zone: [Circular],
      _parentDelegate: [_ZoneDelegate],
      _forkZS: null,
      _forkDlgt: null,
      _forkCurrZone: null,
      _interceptZS: null,
      _interceptDlgt: null,
      _interceptCurrZone: null,
      _invokeZS: [Object],
      _invokeDlgt: [_ZoneDelegate],
      _invokeCurrZone: [Circular],
      _handleErrorZS: [Object],
      _handleErrorDlgt: [_ZoneDelegate],
      _handleErrorCurrZone: [Circular],
      _scheduleTaskZS: [Object],
      _scheduleTaskDlgt: [_ZoneDelegate],
      _scheduleTaskCurrZone: [Circular],
      _invokeTaskZS: [Object],
      _invokeTaskDlgt: [_ZoneDelegate],
      _invokeTaskCurrZone: [Circular],
      _cancelTaskZS: [Object],
      _cancelTaskDlgt: [_ZoneDelegate],
      _cancelTaskCurrZone: [Circular],
      _hasTaskZS: [Object],
      _hasTaskDlgt: [_ZoneDelegate],
      _hasTaskDlgtOwner: [Circular],
      _hasTaskCurrZone: [Circular]
    }
  },
  task: ZoneTask {
    _zone: Zone {
      _parent: [Zone],
      _name: 'angular',
      _properties: [Object],
      _zoneDelegate: [_ZoneDelegate]
    },
    runCount: 0,
    _zoneDelegates: null,
    _state: 'notScheduled',
    type: 'microTask',
    source: 'Promise.then',
    data: ZoneAwarePromise [Promise] {
      __zone_symbol__state: 0,
      __zone_symbol__value: [HttpErrorResponse]
    },
    scheduleFn: undefined,
    cancelFn: undefined,
    callback: [Function],
    invoke: [Function]
  }
}

I noticed that if I remove the reference to the resolvers in the routing, the page renders correctly (with obvious errors related to the rendering of objects that are resolver-dependent), so I am figuring out that the problem is in the resolvers.

Did you already have this problem and/or do you know how to fix this problem? Thanks in advance.