Navigation events are called twice when using HashLocationStrategy

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Current behavior
When using HashLocationStrategy and change url manually to the one, which is protected by CanActivate guard (this returns false and fire redirect to the other page), navigation events are called twice.

Expected behavior
All navigation event are called once only.

Minimal reproduction of the problem with instructions
Use the demo in http://plnkr.co/edit/4xlYD9wmetG5G0Dvjp0E?p=preview
Open window mode http://run.plnkr.co/plunks/4xlYD9wmetG5G0Dvjp0E/#/component-one
Click Guarded Component Two link - only one NavigationStart and NavigationCancel events logged in console.
Manually change url from /#/component-one to /#/component-two and hit enter - two pair of NavigationStart and NavigationCancel events logged in console.

What is the motivation / use case for changing the behavior?
As the duplication of navigation event causes guards logic to be executed twice (and this may contain API calls) - it is a performance issue. Potentially, if guard resolving depends on some conditions which are true after first failed attempt - the second one will be successful, however it is not desired behavior.

Please tell us about your environment:

Angular version: 4.1.0
Browser: Chrome 57
Language: TypeScript

@jasonhodges

No activity or solution in months? This bug still exists. @jasonhodges Is this still on Angulars radar? Its a significant bug, in my opinion.

Duplicate issue at #18366

Getting five NavigationEnd events fired when

router.events.subscribe((val) => {
            if (val instanceof NavigationEnd) {
                console.log('NavigationEnd!');
            }
        });

have same problem.
i planning update to 5 version, maybe this will help

Have the same problem. Use Angular version: 5.2.2 and Typescript 2.6.2

Same here with Angular 5.
Any update on this?
I pretty sure this issue is braking the back button click in the browser getting A->B->C and looping between B and C with the back button click in browser.

I have the same problem. Angular version 5.2.9

is there any update ??

I am able to work around this issue but I am also very interested in a fix.

@jfox459 can u please provide your work around ?

fix(router): fix navigation ignoring logic to compare to the browser …

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fix(router): ensure duplicate popstate/hashchange events are handled …

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Navigation events are called twice when using HashLocationStrategy #16710

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Navigation events are called twice when using HashLocationStrategy #16710

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IAMtheIAM commented on Oct 12, 2017

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angular-automatic-lock-bot commented on Aug 13, 2020

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