One of the better things about Angular2 which had already present in Angular1 was the outputting of meaningful errors whenever they happened within the framework. Unfortunately with the new angular-cli webpack based build, it’s not always easy to understand what is happening with certain errors. Consider this error I recently ran into:

error_handler.js:47 EXCEPTION: Uncaught (in promise): TypeError: Cannot read property ‘_outlets’ of undefined
TypeError: Cannot read property ‘_outlets’ of undefined
at http://localhost:4200/main.bundle.js:13434:56
at forEach (http://localhost:4200/main.bundle.js:5950:13)
at PreActivation.deactiveRouteAndItsChildren (http://localhost:4200/main.bundle.js:13433:99)
at http://localhost:4200/main.bundle.js:13435:19
at forEach (http://localhost:4200/main.bundle.js:5950:13)
at PreActivation.deactiveRouteAndItsChildren (http://localhost:4200/main.bundle.js:13433:99)
at http://localhost:4200/main.bundle.js:13435:19
at forEach (http://localhost:4200/main.bundle.js:5950:13)
at PreActivation.deactiveRouteAndItsChildren (http://localhost:4200/main.bundle.js:13433:99)
at PreActivation.traverseRoutes (http://localhost:4200/main.bundle.js:13418:22)

Can you figure out what is going on? I could not for a while, this happened while trying ti lazy load a module. I checked the component rendered by the path and the <router-outlet> tags where present as expected. It’s not until I checked the component class file that I found a line that did this:

this.router.navigate([‘session’], { relativeTo: this.activatedRoute });

Within the ngOnInit. Bingo! The session path did not exist within all my route definitions.

So the next time this happens to you make sure you are trying to navigate to a path that actually exists in your route definitions.