# Understanding an Enzyme Warning Message

**URL:** https://discourse.julialang.org/t/understanding-an-enzyme-warning-message/102825
**Category:** Optimization (Mathematical)
**Tags:** sciml, enzyme
**Created:** [August 15, 2023, 11:52am UTC](https://discourse.julialang.org/t/understanding-an-enzyme-warning-message/102825 "2023-08-15T11:52:58Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![wsmoses](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/wsmoses/32/26497_2.png) [@wsmoses](https://discourse.julialang.org/u/wsmoses)
#### Post date: [August 15, 2023, 7:38pm UTC](https://discourse.julialang.org/t/understanding-an-enzyme-warning-message/102825/2 "2023-08-15T19:38:18Z")

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That error indicates that you have a type unstable construction of an object, which contains both type unstable non-differentiated data and type unstable differentiated data.

We specifically do not support that yet, so we throw an error rather than risking an incorrect answer.

On 1.10+ you should get a nicer backtrace showing fully the context of where it’s happening.

Perhaps update that area of the code to be type stable (which regardless would be good for performance too)?

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