Invalid Gurobi license

[nslosse]

Hello,

I have installed a fresh version of Gurobi.jl and JuMP for Julia Version 1.3.1 on a linux server.

When making call to Gurobi 9.0 from Julia, I bump on the following error message :

ERROR: LoadError: Invalid Gurobi license

After some research on the internet, I have checked that :

• my Gurobi license file was valid (N.B. this is an evaluation licence)
• all environment variable are properly set
• gurobi works well on its own or when used embedded in python.

Do you have any idea what may cause this error ?

Thank you in advance,

Nicolas Slosse

[odow]

Does your license support Gurobi 9.0? Did you set the GRB_LICENSE_FILE environment variable? You can check with ENV["GRB_LICENSE_FILE"].

From Gurobi.jl point of view, Gurobi.jl is installed and able to communicate with the binary.

[nslosse]

Hi Odow, I confirm that both the environment variable is set that my license file is OK for gurobi 9.0, which I can run in standalone mode anyway.

After some tests, I did observe the following behaviour : I have launched a stand-alone gurobi task in the background and launched another gurobi model via Julia. Julia does crash at this instruction

model = Model(Gurobi.Optimizer)

Whereas without the Gurobi instance running, it would crash at this line

optimize!(model)

It's actually acting like Julia is making twice the gurobi license check. Maybe that causes the issue ?

Regards,

Nicolas

[odow]

Oh. I missed the server part. You probably need to use https://github.com/JuliaOpt/Gurobi.jl#reusing-the-same-gurobi-environment-for-multiple-solves.

const env = Gurobi.Env()  # Do ONE license check
model = Model(() -> Gurobi.Optimizer(env))

[nslosse]

Hi Odow,

Thanks, that was indeed the issue (I just got the same answer from the Gurobi's helpdesk).

Many thanks,

Nicolas

[odow]

Glad you got it sorted.

[ccoffrin]

For anyone that may come across this thread, you may run into issues if running the same script multiple times, for example while doing model development. In that case, I have used the following approach for defining the env constant,

if !(@isdefined env)
    const env = Gurobi.Env()
end