# Serious Observable bug in 0.25

**URL:** <https://forums.fusetools.com/t/serious-observable-bug-in-0-25/5422>\
**Category:** Bug Reports\
**Created:** [August 25, 2016, 6:30pm UTC](https://forums.fusetools.com/t/serious-observable-bug-in-0-25/5422 "2016-08-25T18:30:20Z")\
**Posts on this page:** 5\
**Page:** 2

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**Author:** ![Costin\_Bereveanu](https://yyz1.discourse-cdn.com/flex035/user_avatar/forums.fusetools.com/costin_bereveanu/32/628_2.png) [@Costin\_Bereveanu](https://forums.fusetools.com/u/Costin_Bereveanu)\
**Post date:** [November 3, 2016, 9:10am UTC](https://forums.fusetools.com/t/serious-observable-bug-in-0-25/5422/21 "2016-11-03T09:10:10Z")

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Just lost about an hour again because of this. Didn’t recognise it from the start:  
I have a Panel which is displayed based on a `display` JS Observable.  
The Observable is set asynchronously, if a flag file doesn’t exist. The check was done in an Activated handler. It would just set display.value = true, if the flag is not there.  
Yet, only on restarts the Panel would show. Even if the Activated trigger executes on each page load. Why? Because the `display` Observable gets detached and sequential value changes don’t trigger the WhileTrue I was using to toggle visibility.  
This is a serious limitation for `Activated` - you can only use it for non reactive stuff or only for one time value setting…

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**Author:** ![Anders\_Lassen](https://yyz1.discourse-cdn.com/flex035/user_avatar/forums.fusetools.com/anders_lassen/32/522_2.png) [@Anders\_Lassen](https://forums.fusetools.com/u/Anders_Lassen)\
**Post date:** [November 3, 2016, 9:21am UTC](https://forums.fusetools.com/t/serious-observable-bug-in-0-25/5422/22 "2016-11-03T09:21:41Z")

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Costin: Okay, sorry to hear that. Do you have an isolated test case that shows this issue? If so, I can do some debugging on this.

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<div class="post-metadata">

**Author:** ![Costin\_Bereveanu](https://yyz1.discourse-cdn.com/flex035/user_avatar/forums.fusetools.com/costin_bereveanu/32/628_2.png) [@Costin\_Bereveanu](https://forums.fusetools.com/u/Costin_Bereveanu)\
**Post date:** [November 3, 2016, 9:24am UTC](https://forums.fusetools.com/t/serious-observable-bug-in-0-25/5422/23 "2016-11-03T09:24:02Z")

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Yo Anders! The test case at the top still holds, even if it refers to navigation. It seems it’s more an Observable and Activated issue, than anything else.

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**Author:** ![Anders\_Lassen](https://yyz1.discourse-cdn.com/flex035/user_avatar/forums.fusetools.com/anders_lassen/32/522_2.png) [@Anders\_Lassen](https://forums.fusetools.com/u/Anders_Lassen)\
**Post date:** [November 3, 2016, 9:47am UTC](https://forums.fusetools.com/t/serious-observable-bug-in-0-25/5422/24 "2016-11-03T09:47:31Z")

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Thanks. I’ve reproduced the problem. This is indeed strange, so raising this to top priority.

I’ll keep you posted.

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<div class="post-metadata">

**Author:** ![Anders\_Lassen](https://yyz1.discourse-cdn.com/flex035/user_avatar/forums.fusetools.com/anders_lassen/32/522_2.png) [@Anders\_Lassen](https://forums.fusetools.com/u/Anders_Lassen)\
**Post date:** [November 3, 2016, 10:01am UTC](https://forums.fusetools.com/t/serious-observable-bug-in-0-25/5422/25 "2016-11-03T10:01:23Z")

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Whops, this is an embarrasing one.

Indeed, the `onActivated` function on the _previous_ module was called due to a missing cache invalidation in the event binding system.

**This is now fixed!**

Due to the embarrasingness of this bug, we’ll attempt to get it cherry-picked onto release 0.29, about to go out very soon (today, you can find it in #pre-release-testing on slack).

Thanks so much for reporting this issue and patiently pushing it forward.

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