# Question about JuMP

**URL:** <https://discourse.julialang.org/t/question-about-jump/50675>\
**Category:** Optimization (Mathematical)\
**Tags:** question\
**Created:** [November 24, 2020, 7:39am UTC](https://discourse.julialang.org/t/question-about-jump/50675 "2020-11-24T07:39:59Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![abcde](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/abcde/32/16180_2.png) [@abcde](https://discourse.julialang.org/u/abcde)\
**Post date:** [November 24, 2020, 7:39am UTC](https://discourse.julialang.org/t/question-about-jump/50675/1 "2020-11-24T07:39:59Z")

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there is something wrong with my JuMP!  
 ![image](https://global.discourse-cdn.com/julialang/original/3X/0/0/00375deab7776262248e81adac3ca68f294a15df.png)

 ![image](https://global.discourse-cdn.com/julialang/original/3X/7/4/74dd7cb7c0524c4c97b89a316967a43d6f4f082e.png)  
It used to work!why? 😣  
thank you!

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**Author:** ![mike\_k](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mike_k/32/211864_2.png) [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Post date:** [November 24, 2020, 9:18am UTC](https://discourse.julialang.org/t/question-about-jump/50675/2 "2020-11-24T09:18:49Z")

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Looks like some package version conflict with `CapacityExpansion`, `JuMP`, and/or `BiLevelJuMP`. At least when I install `CapcityExpansion` it downgrades the preinstalled `JuMP` to version 0.19.2.  
You could try to remove these packages and re-install them. You may also try to add these packages in an empty project-environment, and see what happens.

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**Author:** ![abcde](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/abcde/32/16180_2.png) [@abcde](https://discourse.julialang.org/u/abcde)\
**Post date:** [November 26, 2020, 5:52am UTC](https://discourse.julialang.org/t/question-about-jump/50675/3 "2020-11-26T05:52:46Z")

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thanks！it works! 😀

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**Author:** ![odow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/odow/32/28685_2.png) [@odow](https://discourse.julialang.org/u/odow)\
**Post date:** [November 26, 2020, 6:52am UTC](https://discourse.julialang.org/t/question-about-jump/50675/4 "2020-11-26T06:52:42Z")

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Here’s the issue: [https://github.com/YoungFaithful/CapacityExpansion.jl/issues/25](https://github.com/YoungFaithful/CapacityExpansion.jl/issues/25).

@abcde If you need CapacityExpansion.jl with JuMP 0.21, it’s probably not too much work to help them update. Probably mostly just a few find-and-replaces.