# ERROR: type DataType has no field optimizer\_constructor
**URL:** https://discourse.julialang.org/t/error-type-datatype-has-no-field-optimizer-constructor/47920
**Category:** Optimization (Mathematical)
**Tags:** jump, error
**Created:** [October 7, 2020, 11:37am UTC](https://discourse.julialang.org/t/error-type-datatype-has-no-field-optimizer-constructor/47920 "2020-10-07T11:37:08Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@umbe](https://discourse.julialang.org/u/umbe)
#### Post date: [October 7, 2020, 11:37am UTC](https://discourse.julialang.org/t/error-type-datatype-has-no-field-optimizer-constructor/47920/1 "2020-10-07T11:37:08Z")
Hi everyone,
I’m having a problem with JuMP/Juniper.
For first I create an optimization model
```julia
m = Model(Juniper.Optimizer)
set_optimizer_attribute(m, "nl_solver", Ipopt.Optimizer)
set_optimizer_attribute(m, "mip_solver", Cbc.Optimizer)
```
and then I define all the variables and constraints. Up to this point everithing is ok.
Successively, I run the optimization. The solver starts to print its outputs in the REPL until it ends, since the convergence is reached.
```julia
EXIT: Optimal Solution Found.
Status of relaxation: LOCALLY_SOLVED
```
However, immediatly after that, the following error appears:
```julia
ERROR: type DataType has no field optimizer_constructor
Stacktrace:
[1] getproperty(::Type{T} where T, ::Symbol) at .\Base.jl:28
[2] generate_mip(::Juniper.Optimizer, ::Juniper.JuniperProblem, ::Array{Float64,1}, ::Juniper.TabuList, ::Float64) at C:\Users\user1\.julia\packages\Juniper\Hm6I1\src\fpump.jl:9
[3] fpump(::Juniper.Optimizer, ::Juniper.JuniperProblem) at C:\Users\user1\.julia\packages\Juniper\Hm6I1\src\fpump.jl:360
[4] optimize!(::Juniper.Optimizer) at C:\Users\user1\.julia\packages\Juniper\Hm6I1\src\MOI_wrapper\MOI_wrapper.jl:413
[5] optimize!(::MathOptInterface.Bridges.LazyBridgeOptimizer{Juniper.Optimizer}) at C:\Users\user1\.julia\packages\MathOptInterface\bygN7\src\Bridges\bridge_optimizer.jl:239
[6] optimize!(::MathOptInterface.Utilities.CachingOptimizer{MathOptInterface.AbstractOptimizer,MathOptInterface.Utilities.UniversalFallback{MathOptInterface.Utilities.Model{Float64}}}) at C:\Users\user1\.julia\packages\MathOptInterface\bygN7\src\Utilities\cachingoptimizer.jl:189
[7] optimize!(::Model, ::Nothing; bridge_constraints::Bool, ignore_optimize_hook::Bool, kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at C:\Users\user1\.julia\packages\JuMP\YXK4e\src\optimizer_interface.jl:131
[8] optimize! at C:\Users\user1\.julia\packages\JuMP\YXK4e\src\optimizer_interface.jl:107 [inlined] (repeats 2 times)
[9] top-level scope at none:0
```
and the optimization results are not provided.
Unfortunately, I have no idea what it means and looking on the web I did not find anything useful.
Does anyone know what is going wrong?
---
### Author:  [@ccoffrin](https://discourse.julialang.org/u/ccoffrin)
#### Post date: [October 7, 2020, 3:14pm UTC](https://discourse.julialang.org/t/error-type-datatype-has-no-field-optimizer-constructor/47920/2 "2020-10-07T15:14:41Z")
This error is a bit of mystery to me. You might try something like,
```julia
set_optimizer_attribute(m, "mip_solver", optimizer_with_attributes(Cbc.Optimizer, "logLevel" => 0))
```
That is how we test the solver. Note that the MIP solver is only used in the feasibility pump, so you can also try omitting it entierly.
@Wikunia, do you have any other suggestions?
---
### Author:  [@Wikunia](https://discourse.julialang.org/u/Wikunia)
#### Post date: [October 7, 2020, 3:24pm UTC](https://discourse.julialang.org/t/error-type-datatype-has-no-field-optimizer-constructor/47920/3 "2020-10-07T15:24:34Z")
That’s indeed interesting. I think we never tested it that way as we weren’t interested in the long output of the subsolvers. I hope the suggestion by @ccoffrin works for you.
I’m currently on vacation but I can have a look into it next week. Maybe open an issue on our repo such that I don’t forget it.
---
### Author:  [@umbe](https://discourse.julialang.org/u/umbe)
#### Post date: [October 8, 2020, 2:54pm UTC](https://discourse.julialang.org/t/error-type-datatype-has-no-field-optimizer-constructor/47920/4 "2020-10-08T14:54:40Z")
Thank you very much @ccoffrin and @Wikunia!
I suppressed the solvers output by writing
```julia
optmod = Model(with_optimizer(Juniper.Optimizer;
nl_solver = with_optimizer(Ipopt.Optimizer, print_level = 0),
mip_solver = with_optimizer(Cbc.Optimizer, logLevel = 0)))
```
and the solver ran properly.
As you suggested, I opened [an issue](https://github.com/lanl-ansi/Juniper.jl/issues/201) on the Juniper repository.
Thank you again for your support!