# \[BUG - 14374\] Expression Error - Unknown function: 'hasChanged'

**URL:** <https://forum.inductiveautomation.com/t/bug-14374-expression-error-unknown-function-haschanged/26340>\
**Category:** Ignition Early Access\
**Created:** [July 8, 2019, 5:34am UTC](https://forum.inductiveautomation.com/t/bug-14374-expression-error-unknown-function-haschanged/26340 "2019-07-08T05:34:08Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![tgfgreaves](https://avatars.discourse-cdn.com/v4/letter/t/919ad9/32.png) [@tgfgreaves](https://forum.inductiveautomation.com/u/tgfgreaves)\
**Post date:** [July 8, 2019, 5:34am UTC](https://forum.inductiveautomation.com/t/bug-14374-expression-error-unknown-function-haschanged/26340/1 "2019-07-08T05:34:08Z")

</div>

I am trying to implement a counter for a tag. Currently the units tags are created through perspective session due the future scaling. As such, i require the counter to be created dynamically at the same time a new units tags are created, hence why an expression tag is being used.  
I need to add 1 to a ‘Count’ tag whenever another tag becomes 1.  
For some reason i cannot get ‘hasChanged’ to cooperate.  
Is this function bugged and if so, when is it expected to be available again?

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/2X/f/f1985de0b8234344da7a24ca362015ed09f92626.png)  
 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/2X/9/9d53121b2c572ea4cad04d5e5659e79301eebbbc.png)

---

<div class="post-metadata">

**Author:** ![KathyApplebaum](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kathyapplebaum/32/7261_2.png) [@KathyApplebaum](https://forum.inductiveautomation.com/u/KathyApplebaum)\
**Post date:** [July 8, 2019, 2:20pm UTC](https://forum.inductiveautomation.com/t/bug-14374-expression-error-unknown-function-haschanged/26340/2 "2019-07-08T14:20:52Z")

</div>

I don’t see any current bug reports on it, but I’m able to replicate the issue in 8.0.3. I’ll open a ticket for this. Thanks!

---

<div class="post-metadata">

**Author:** ![awalker](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/awalker/32/6874_2.png) [@awalker](https://forum.inductiveautomation.com/u/awalker)\
**Post date:** [July 26, 2019, 3:34pm UTC](https://forum.inductiveautomation.com/t/bug-14374-expression-error-unknown-function-haschanged/26340/3 "2019-07-26T15:34:43Z")

</div>

This issue was fixed in the 8.0.4 Nightly build that was uploaded today (7/26).