"Please load the corresponding AD package Symbolics"

[jariji]

It says to load Symbolics but I have loaded it already.

Julia 1.10.3

⌃ [a0c0ee7d] DifferentiationInterface v0.5.11
  [f6369f11] ForwardDiff v0.10.36
  [7f7a1694] Optimization v3.27.0
  [36348300] OptimizationOptimJL v0.3.2
⌅ [0c5d862f] Symbolics v5.36.0

julia> using DifferentiationInterface, Symbolics, Optimization, OptimizationOptimJL, ForwardDiff

julia> let f(x,_) = x'x
           optfunc = OptimizationFunction(f, DifferentiationInterface.AutoForwardDiff())
           optprob = OptimizationProblem(optfunc, [4.0])
           solve(optprob, LBFGS())
       end
retcode: Success
u: 1-element Vector{Float64}:
 0.0

julia> let f(x,_) = x'x
           optfunc = OptimizationFunction(f, DifferentiationInterface.AutoSymbolics())
           optprob = OptimizationProblem(optfunc, [4.0])
           solve(optprob, LBFGS())
       end
ERROR: ArgumentError: The passed automatic differentiation backend choice is not available. Please load the corresponding AD package Symbolics.
Stacktrace:
  [1] instantiate_function(f::Function, x::OptimizationBase.ReInitCache{…}, adtype::AutoSymbolics, p::Int64, num_cons::Int64)
    @ OptimizationBase ~/.julia/packages/OptimizationBase/mGHPN/src/function.jl:114
  [2] instantiate_function(f::Function, x::OptimizationBase.ReInitCache{…}, adtype::AutoSymbolics, p::Int64)
    @ OptimizationBase ~/.julia/packages/OptimizationBase/mGHPN/src/function.jl:106
  [3] OptimizationCache(prob::OptimizationProblem{…}, opt::LBFGS{…}, data::Base.Iterators.Cycle{…}; callback::Function, maxiters::Nothing, maxtime::Nothing, abstol::Nothing, reltol::Nothing, progress::Bool, structural_analysis::Bool, manifold::Nothing, kwargs::@Kwargs{})
    @ OptimizationBase ~/.julia/packages/OptimizationBase/mGHPN/src/cache.jl:38
  [4] __init(prob::OptimizationProblem{…}, opt::LBFGS{…}, data::Base.Iterators.Cycle{…}; callback::Function, maxiters::Nothing, maxtime::Nothing, abstol::Nothing, reltol::Nothing, progress::Bool, kwargs::@Kwargs{})
    @ OptimizationOptimJL ~/.julia/packages/OptimizationOptimJL/hDX5k/src/OptimizationOptimJL.jl:112
  [5] __init(prob::OptimizationProblem{…}, opt::LBFGS{…}, data::Base.Iterators.Cycle{…})
    @ OptimizationOptimJL ~/.julia/packages/OptimizationOptimJL/hDX5k/src/OptimizationOptimJL.jl:77
  [6] init(::OptimizationProblem{…}, ::LBFGS{…}; kwargs::@Kwargs{})
    @ SciMLBase ~/.julia/packages/SciMLBase/vhP5T/src/solve.jl:174
  [7] init(::OptimizationProblem{…}, ::LBFGS{…})
    @ SciMLBase ~/.julia/packages/SciMLBase/vhP5T/src/solve.jl:172
  [8] solve(::OptimizationProblem{…}, ::LBFGS{…}; kwargs::@Kwargs{})
    @ SciMLBase ~/.julia/packages/SciMLBase/vhP5T/src/solve.jl:96
  [9] solve(::OptimizationProblem{…}, ::LBFGS{…})
    @ SciMLBase ~/.julia/packages/SciMLBase/vhP5T/src/solve.jl:93
 [10] top-level scope

[gdalle]

Maybe this is linked to the fact that the corresponding backend was called AutoModelingToolkit before? @Vaibhavdixit02

[Vaibhavdixit02]

The error message is too naive sorry about that. You need to load ModelingToolkit to be able to use this since the extension is for MTK

[jariji]

Yep that works, thanks.