# Warning invalid warm start GLPK

**URL:** <https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441>\
**Category:** Optimization (Mathematical)\
**Tags:** question, jump\
**Created:** [September 11, 2020, 8:32am UTC](https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441 "2020-09-11T08:32:32Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![ErwanPiR](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/erwanpir/32/11434_2.png) [@ErwanPiR](https://discourse.julialang.org/u/ErwanPiR)\
**Post date:** [September 11, 2020, 8:32am UTC](https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441/1 "2020-09-11T08:32:32Z")

</div>

Hi,

I see some topics dated from 2019 talking about the warm start in JuMP with GLPK. I still have the warning :

```julia
Warning: MathOptInterface.VariablePrimalStart() is not supported by MathOptInterface.Bridges.LazyBridgeOptimizer{GLPK.Optimizer}.

```

when `using set_start_value`  
I don’t understand since the merged seems to have been done (see [https://github.com/jump-dev/GLPK.jl/pull/101](https://github.com/jump-dev/GLPK.jl/pull/101) )

I am using JuMP v.0.21.3, GLPK v.0.13.0 and GLPKMAthProgInterface v.0.5.0

Someone knows if there is another way to fill a start value to the solver ?

Thanks for your help.  
Erwan

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<div class="post-metadata">

**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:** [September 13, 2020, 9:11pm UTC](https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441/2 "2020-09-13T21:11:21Z")

</div>

Please provide a reproducible example. `GLPKMathProgInterface` is deprecated. You should just use `GLPK.Optimizer`.

---

<div class="post-metadata">

**Author:** ![greg\_plowman](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/greg_plowman/32/8100_2.png) [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)\
**Post date:** [March 11, 2021, 1:31am UTC](https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441/3 "2021-03-11T01:31:56Z")

</div>

Here’s an example of a warning when using `set_start_value` with `GLPK`.

```julia
┌ Warning: MathOptInterface.VariablePrimalStart() is not supported by MathOptInterface.Bridges.LazyBridgeOptimizer{GLPK.Optimizer}. This information will be discarded.
└ @ MathOptInterface.Utilities C:\Users\plowman\.julia\packages\MathOptInterface\5WwpK\src\Utilities\copy.jl:285

```

```julia
Julia 1.5.3, Julia 1.6.0-rc1
JuMP v0.21.6
GLPK v0.14.7

```

```julia
using JuMP, GLPK

model = Model(GLPK.Optimizer)

x = [1,2,3]
@variable(model, w[1:3] >= 1, Int)
set_start_value.(w, [2,2,6])
start_value.(w)

@constraint(model, sum(w) == 10)
@objective(model, Min, sum(x[i] * w[i] for i in 1:3))
optimize!(model)

println("Objective value: ", objective_value(model))
println("Weights: ", value.(model[:w]))

```

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<div class="post-metadata">

**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:** [March 11, 2021, 2:20am UTC](https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441/4 "2021-03-11T02:20:50Z")

</div>

Looks like I forgot to update this thread.

The warning is correct. GLPK does not support warm starts.