# Physics gravity issue after migration 3.2.0 =\> 4.0.0

**URL:** <https://forum.babylonjs.com/t/physics-gravity-issue-after-migration-3-2-0-4-0-0/2251>\
**Category:** Questions\
**Created:** [March 31, 2019, 10:50am UTC](https://forum.babylonjs.com/t/physics-gravity-issue-after-migration-3-2-0-4-0-0/2251 "2019-03-31T10:50:34Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![splash27](https://avatars.discourse-cdn.com/v4/letter/s/76d3ee/32.png) [@splash27](https://forum.babylonjs.com/u/splash27)\
**Post date:** [April 2, 2019, 3:49pm UTC](https://forum.babylonjs.com/t/physics-gravity-issue-after-migration-3-2-0-4-0-0/2251/7 "2019-04-02T15:49:53Z")

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Unfortunately, it is imposible to reproduce in playground. Because in playground `scene.enablePhysics()` doesn’t cause ‘CANNON is undefined’ error.

And I have NO NEED to do like that:

```auto
let cannonPlugin = new BABYLON.CannonJSPlugin(true, 10, cannon);
scene.enablePhysics(scene.gravity, cannonPlugin);

```

So, my first example works good both at 3.2 and 4.0 if we work inside playground. But on my computer it causes ‘CANNON is undefined’ error.

I think I have situation like described in this ticket: [Cannon.js NPM "CANNON is not defined" in v4.0.0-alpha.21 but works in v4.0.0-alpha.16](https://forum.babylonjs.com/t/cannon-js-npm-cannon-is-not-defined-in-v4-0-0-alpha-21-but-works-in-v4-0-0-alpha-16/844)  
I’ve took a solution how to fix crash from there but it caused gravity problems, that I mentioned above.

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