# Variables declaration in JuliaPro 1.5.2-1

**URL:** <https://discourse.julialang.org/t/variables-declaration-in-juliapro-1-5-2-1/47802>\
**Category:** Optimization (Mathematical)\
**Tags:** question\
**Created:** [October 5, 2020, 4:52pm UTC](https://discourse.julialang.org/t/variables-declaration-in-juliapro-1-5-2-1/47802 "2020-10-05T16:52:39Z")\
**Posts on this page:** 1\
**Showing post:** 13

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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:** [October 6, 2020, 7:58pm UTC](https://discourse.julialang.org/t/variables-declaration-in-juliapro-1-5-2-1/47802/13 "2020-10-06T19:58:44Z")

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After updating packages, you need to close Julia and re-open for the changes to take effect. You need JuMP 0.21 for `Model(Cbc.Optimizer)` to work.

Note that discourse has a search function. This question has been asked multiple times recently:

> [@ERROR: MethodError: no method matching Model](https://discourse.julialang.org/t/error-methoderror-no-method-matching-model/45699):
>
> Hello, I’m new in Julia and JuMP and I just tried to install and test JuMP but I got this error (with all solvers that I tested): julia\> Model(Gurobi.Optimizer) ERROR: MethodError: no method matching Model(::Type{Gurobi.Optimizer}) Closest candidates are: Model(::Any, ::Any, ::Any, ::Any, ::Any, ::Any, ::Any, ::Any) at …

> [@Optimization errors with simple JuMP function using GLPK Optimizer](https://discourse.julialang.org/t/optimization-errors-with-simple-jump-function-using-glpk-optimizer/46652):
>
> Hello, I am a novice to Julia programming. Going though a tutorial I see myself running into this error and I am not quite sure what it means. Can someone who is an expert in JuMP and GLPK advise? Error: MethodError: no method matching Model(::Type{GLPK.Optimizer}) Code: using Interact using Plots using JuMP, GLPK # Define some input data about the test system # Maximum power output of generators const GENERATION\_MAX = [1000, 1000] # Minimum power output of generators const GENERATION\_MIN =…

> [@JuMP Stopped Working Today](https://discourse.julialang.org/t/jump-stopped-working-today/46348):
>
> Hi, I’ve been using JuMP for a project and it stopped working today after I installed Gurobi. I get ERROR: LoadError: MethodError: no method matching Model(::Type{Gurobi.Optimizer}) when I set the solver to Gurobi, but it is also doing this for Ipopt. I have tried downgrading/upgrading the package versions but the same error keeps occurring. What could be causing this? Thanks.

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