# Reading JuMP model "lower bound already set"
**URL:** https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156
**Category:** Optimization (Mathematical)
**Tags:** jump
**Created:** [March 15, 2023, 11:09pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156 "2023-03-15T23:09:30Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@shakedregev](https://discourse.julialang.org/u/shakedregev)
#### Post date: [March 15, 2023, 11:09pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/1 "2023-03-15T23:09:30Z")
Writing the model like this works
```julia
model = JuMP.Model(Clarabel.Optimizer)
*set variables and contraints*
write_to_file(model, "my_model.lp")
```
The model is also solved correctly by Clarabel. However, problems occur when I try to read it.
```julia
model = read_from_file("my_model.lp")
set_optimizer(model, Clarabel.Optimizer)
optimize!(model)
```
I get the error:
```julia
LoadError: MathOptInterface.LowerBoundAlreadySet{MathOptInterface.Interval{Float64}, MathOptInterface.GreaterThan{Float64}}: Cannot add `VariableIndex`-in-`MathOptInterface.GreaterThan{Float64}` constraint for variable MathOptInterface.VariableIndex(1) as a `VariableIndex`-in-`MathOptInterface.Interval{Float64}` constraint was already set for this variable and both constraints set a lower bound.
```
These 3 lines are all I’m doing in the read portion. Also, it throws the same error if I get rid of the second line.
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [March 15, 2023, 11:18pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/2 "2023-03-15T23:18:12Z")
Can you provide a reproducible example? What is the contents of `my_model.lp`?
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [March 15, 2023, 11:39pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/3 "2023-03-15T23:39:53Z")
This is an embarrassing bug! Let me take a look.
```julia
julia> using JuMP
julia> model = Model();
julia> @variable(model, 0 <= x <= 1)
x
julia> write_to_file(model, "model.lp")
julia> read_from_file("model.lp")
ERROR: MathOptInterface.LowerBoundAlreadySet{MathOptInterface.Interval{Float64}, MathOptInterface.GreaterThan{Float64}}: Cannot add `VariableIndex`-in-`MathOptInterface.GreaterThan{Float64}` constraint for variable MathOptInterface.VariableIndex(1) as a `VariableIndex`-in-`MathOptInterface.Interval{Float64}` constraint was already set for this variable and both constraints set a lower bound.
Stacktrace:
```
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [March 16, 2023, 1:16am UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/4 "2023-03-16T01:16:56Z")
Fixed in [[FileFormats.LP] fix reading models with default bounds by odow · Pull Request #2121 · jump-dev/MathOptInterface.jl · GitHub](https://github.com/jump-dev/MathOptInterface.jl/pull/2121).
I’ll get a new release tagged in the next day or so.
---
### Author:  [@shakedregev](https://discourse.julialang.org/u/shakedregev)
#### Post date: [March 16, 2023, 5:37pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/5 "2023-03-16T17:37:27Z")
Thanks, I tried using the package manager to add the branch you linked here
```julia
add MathOptInterface#od/fix-lp-read
```
This worked with no issues, but then I got the same error when running my code. Not sure if I am not doing it correctly or if it just hasn’t been updated.
Edit: I think the problem is that it hasn’t been updated properly in my package directory
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [March 16, 2023, 7:27pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/6 "2023-03-16T19:27:17Z")
> Not sure if I am not doing it correctly or if it just hasn’t been updated.
After updating a package, you need to restart Julia for the change to take effect.
If it’s still a problem after that, can you provide a reproducible example?
Note that I merged the branch, so now you need `] add MathOptInterface#master`.
---
### Author:  [@shakedregev](https://discourse.julialang.org/u/shakedregev)
#### Post date: [March 16, 2023, 9:32pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/7 "2023-03-16T21:32:20Z")
Thanks, that worked!
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [March 16, 2023, 9:49pm UTC](https://discourse.julialang.org/t/reading-jump-model-lower-bound-already-set/96156/8 "2023-03-16T21:49:20Z")
We’ll tag the fix in the next day or so. Just waiting for a couple of other things: [Prep for v1.13.2 by odow · Pull Request #2122 · jump-dev/MathOptInterface.jl · GitHub](https://github.com/jump-dev/MathOptInterface.jl/pull/2122).
Sorry for the bug! It turns out we could read and write LP files, but we couldn’t read some of our own LP files…