Angular 7 - Multiple outlets : Error: Cannot activate an already activated outlet

Question

Here is the issue that I'm encountering with Angular 7 :

I have two outlets : the main app router outlet, and a secondary outlet named 'administration'.

When I want to navigate through any administration link at start, it works fine. But next time, when I try to navigate, angular throws this error message :

Error: Cannot activate an already activated outlet

So, can someone explain me why ? I haven't found any solution on forums...

Here is a stackblitz : https://stackblitz.com/edit/angular-osnnd4

Thank you all everybody :)

Answer 1

The problem occurs when lazyloading child routes. You have to manually deactivate the outlet everytime you change a route.

I have modified your AdministrationComponent to workaround as follow. It should be able to work for now, until Angular have a way to solve the problem.

import { Component, OnInit, ViewChild } from '@angular/core';
import { RouterOutlet, Router, ActivationStart } from '@angular/router';

@Component({
  selector: 'app-administration',
  templateUrl: './administration.component.html',
  styleUrls: ['./administration.component.css']
})
export class AdministrationComponent implements OnInit {

  @ViewChild(RouterOutlet) outlet: RouterOutlet;

  constructor(
    private router: Router
  ) { }

  ngOnInit(): void {
    this.router.events.subscribe(e => {
      if (e instanceof ActivationStart && e.snapshot.outlet === "administration")
        this.outlet.deactivate();
    });
  }
}