ERROR: type SCCNonlinearProblem has no field kwargs

[bradcarman]

The following produces the error: type SCCNonlinearProblem has no field kwargs

using ModelingToolkit
using ModelingToolkit: D_nounits as D, t_nounits as t
using OrdinaryDiffEq

reg_pow(x, a, delta = 0.1) = ifelse(abs(x/delta) >= 1, sign(x)*abs(x/delta)^a * delta^a, (delta^a*x)/delta)

function System(; name)
    pars = @parameters begin
        ρ₀ = 1000
        β = 2e9
        A = 0.1
        m = 100
        L = 1
    
        p_s = 100e5
        p_r = 10e5
        C1 = 1.35
        C2 = 1.35
        c = 1000
        A_p = 0.00094
    
        transition=0.1
    end   
    vars = @variables begin
        p_1(t) = p_s
        p_2(t) = p_r
        x(t)=0
        dx(t)=0
        ddx(t), [guess=0]
        rho_1(t), [guess=ρ₀]
        rho_2(t), [guess=ρ₀]
        drho_1(t), [guess=0]
        drho_2(t), [guess=0]
        m_1(t), [guess=0]
        m_2(t), [guess=0]
        u_1(t), [guess=0]
        u_2(t), [guess=0]
    end
    
    eqs = [
    
        D(x) ~ dx
        D(dx) ~ ddx
    
        D(m_1) ~ u_1*ρ₀*A_p
        D(m_2) ~ u_2*ρ₀*A_p
    
        # volume & mass
        m_1 ~ rho_1*(L+x)*A
        m_2 ~ rho_2*(L-x)*A
    
        # density
        rho_1 ~ ρ₀*(1 + p_1/β)
        rho_2 ~ ρ₀*(1 + p_2/β)
        
        # actuator force balance
        m*ddx ~ (p_1 - p_2)*A - c*dx
        
        # orifices
        (p_s - p_1) ~ C1*ρ₀*reg_pow(u_1, 2)  # orifice 1
        (p_r - p_2) ~ C2*ρ₀*reg_pow(u_2, 2)  # orifice 2
    
    ]
    
    return ODESystem(eqs, t, vars, pars; name)
end

@mtkbuild sys = System()

initprob = ModelingToolkit.InitializationProblem(sys, 0.0)
initsys = solve(initprob) 

The full stacktrace is...

julia> initsys = solve(initprob)
ERROR: type SCCNonlinearProblem has no field kwargs
Stacktrace:
 [1] getproperty(prob::SCCNonlinearProblem{…}, name::Symbol)
   @ SciMLBase C:\Users\bradl\.julia\packages\SciMLBase\XzPx0\src\problems\nonlinear_problems.jl:519
 [2] solve(::SCCNonlinearProblem{…}; sensealg::Nothing, u0::Nothing, p::Nothing, wrap::Val{…}, kwargs::@Kwargs{})
   @ DiffEqBase C:\Users\bradl\.julia\packages\DiffEqBase\R2Vjs\src\solve.jl:1030
 [3] solve(::SCCNonlinearProblem{Vector{…}, false, Vector{…}, Vector{…}, NonlinearFunction{…}, MTKParameters{…}})
   @ DiffEqBase C:\Users\bradl\.julia\packages\DiffEqBase\R2Vjs\src\solve.jl:1028
 [4] top-level scope
   @ c:\Work\Packages\Issue953\initialization.jl:75
Some type information was truncated. Use `show(err)` to see complete types.

Current versions are...

(Issue953) pkg> st
Status `C:\Work\Packages\Issue953\Project.toml`

  [961ee093] ModelingToolkit v9.60.0

  [1dea7af3] OrdinaryDiffEq v6.90.1

[AayushSabharwal]

This is a missing dispatch in NonlinearSolve.jl. It doesn't use the default algorithm, so you need to explicitly provide it:

initsys = solve(initprob, FastShortcutNonlinearPolyalg())

[ChrisRackauckas]

oh 😅 that's easy to fix at least.