# Critical Error - can't find problem

**URL:** <https://community.thunkable.com/t/critical-error-cant-find-problem/2454525>\
**Category:** Questions about Thunkable X\
**Created:** [June 6, 2023, 7:32pm UTC](https://community.thunkable.com/t/critical-error-cant-find-problem/2454525 "2023-06-06T19:32:40Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![tatiang](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/tatiang/32/55482_2.png) [@tatiang](https://community.thunkable.com/u/tatiang)\
**Post date:** [June 6, 2023, 10:41pm UTC](https://community.thunkable.com/t/critical-error-cant-find-problem/2454525/2 "2023-06-06T22:41:45Z")

</div>

Just a side note that you don’t have to check app variables for null values. That’s only something you need to do for stored variables. You could probably simplify that code quite a bit…

But in terms of finding the source of the crash, I’d recommend doing some block-by-block debugging. I have a method I use that works pretty well: [Debugging in Thunkable X (Video)](https://community.thunkable.com/t/debugging-in-thunkable-x-video/849471)

---

_[View the full topic](https://community.thunkable.com/t/critical-error-cant-find-problem/2454525)._