ERROR: MethodError: no method matching view(::MTKParameters) after upgrade to 10.21 from 10.17

[RobbesU]

My MTK model worked fine under 10.17.0 before I went on leave.
After upgrading everything to MTK 10.21.0, I get above MethodError during the ODEProblem() creation step.

As a test I ran the 3637 MWE from this exact same error a while ago: that MWE runs without error so it's another issue.

Expected behavior

ODEProblem() to be created ok as before.

Minimal Reproducible Example 👇
My System, defined in Pluto, is a rather lengthy compilation including parametric functions, so breaking it down to a simple MWE will take significant time. So I'm sort of hoping that the stack trace has the info you need. If not I'll create an MWE (which might not be quite small) and upload to gist. Just ask.
Is there a way I can break down ODEProblem() into smaller steps and see where the error occurs?

Error & Stacktrace ⚠️

MethodError: no method matching view(
::SciMLBase.LinearProblem{
  Vector{Float64}, 
  true, 
  Matrix{Float64}, 
  Vector{Float64}, 
  ModelingToolkit.MTKParameters{
    Vector{Float64}, 
    StaticArraysCore.SizedVector{0, Float64, Vector{Float64}}, 
    Tuple{}, 
    Tuple{Vector{Float64}}, 
    Tuple{}, 
    Tuple{Vector{Float64}}
    }, 
  SciMLBase.SymbolicLinearInterface{
     ModelingToolkit.GeneratedFunctionWrapper{
        (1, 1, true), 
        RuntimeGeneratedFunctions.RuntimeGeneratedFunction{
            (:___mtkparameters___,), 
            ModelingToolkit.var"#_RGF_ModTag", 
            ModelingToolkit.var"#_RGF_ModTag", 
            (0x2c3f7022, 0xc7d55d92, 0x37a04ea8, 0x0cf255a5, 0x12cacc26), 
            Nothing
           }, 
      RuntimeGeneratedFunctions.RuntimeGeneratedFunction{
           (:ˍ₋out, :___mtkparameters___), 
           ModelingToolkit.var"#_RGF_ModTag", 
           ModelingToolkit.var"#_RGF_ModTag", 
           (0xb4f27539, 0x229127e9, 0xbe698f26, 0x219d1033, 0x9d637496), 
           Nothing
           }
     }, 
    ModelingToolkit.GeneratedFunctionWrapper{
         (1, 1, true), 
        RuntimeGeneratedFunctions.RuntimeGeneratedFunction{
              (:___mtkparameters___,), 
              ModelingToolkit.var"#_RGF_ModTag", 
              ModelingToolkit.var"#_RGF_ModTag", 
              (0x6f61882c, 0x8ad26dda, 0x03ef547d, 0x44e7f5b7, 0x6fd8724b), 
              Nothing
              }, 
        RuntimeGeneratedFunctions.RuntimeGeneratedFunction{
             (:ˍ₋out, :___mtkparameters___), 
             ModelingToolkit.var"#_RGF_ModTag", 
             ModelingToolkit.var"#_RGF_ModTag", 
             (0x7ac9c50c, 0x475f4168, 0x6534e784, 0xfba9198a, 0xa6a7a0fc), 
             Nothing}
        }, 
   ModelingToolkit.System, 
   ModelingToolkit.ObservedFunctionCache{ModelingToolkit.System}, 
   Nothing
   }, 
Base.Pairs{
    Symbol, 
    Union{}, 
    Tuple{}, 
    @NamedTuple{}
    }
}, 
::StaticArraysCore.SVector{3, Int64}
)

The function `view` exists, but no method is defined for this combination of argument types.


Closest candidates are:

  view(::ChainRulesCore.AbstractZero, ::Any...)

   @ ChainRulesCore C:\Users\robur\.julia\packages\ChainRulesCore\Vsbj9\src\tangent_types\abstract_zero.jl:44

  view(::RecursiveArrayTools.AbstractVectorOfArray{T, N, <:AbstractVector{T}}, ::Any...) where {T, N, M}

   @ RecursiveArrayTools C:\Users\robur\.julia\packages\RecursiveArrayTools\jieUI\src\vector_of_array.jl:665

  view(::RecursiveArrayTools.AbstractVectorOfArray, ::Any...) where M

   @ RecursiveArrayTools C:\Users\robur\.julia\packages\RecursiveArrayTools\jieUI\src\vector_of_array.jl:676

  ...

Stacktrace

Here is what happened, the most recent locations are first:

    macro expansion
    from 
    code.jl:411
    macro expansion
    from 
    build_function.jl:137
    macro expansion
    from 
    RuntimeGeneratedFunctions.jl:161
    macro expansion
    from 
    generated_callfunc
    from 
    (::RuntimeGeneratedFunctions.RuntimeGeneratedFunction{(:out, :__mtk_arg_1, :___mtkparameters___), ModelingToolkit.var"#_RGF_ModTag", ModelingToolkit.var"#_RGF_ModTag", (0xf991b0f9, 0x93d46755, 0x894ab52c, 0x93768f83, 0x3e9f36c6), Nothing})(::Tuple{Vector{Float64}}, ::Vector{Any}, ::ModelingToolkit.MTKParameters{Vector{Float64}, StaticArraysCore.SizedVector{0, Float64, Vector{Float64}}, Tuple{}, Tuple{Vector{Float64}}, Tuple{}, Tuple{Vector{Float64}}})
    from 
    RuntimeGeneratedFunctions → RuntimeGeneratedFunctions.jl:148
    macro expansion
    from 
    codegen_utils.jl
    _generated_call
    from 
    codegen_utils.jl:353
    GeneratedFunctionWrapper
    from 
    codegen_utils.jl:350
    (::ModelingToolkit.CacheWriter{ModelingToolkit.GeneratedFunctionWrapper{(3, 3, true), RuntimeGeneratedFunctions.RuntimeGeneratedFunction{(:out, :__mtk_arg_1, :___mtkparameters___), ModelingToolkit.var"#_RGF_ModTag", ModelingToolkit.var"#_RGF_ModTag", (0xf991b0f9, 0x93d46755, 0x894ab52c, 0x93768f83, 0x3e9f36c6), Nothing}, Nothing}})(p::ModelingToolkit.MTKParameters{Vector{Float64}, StaticArraysCore.SizedVector{0, Float64, Vector{Float64}}, Tuple{}, Tuple{Vector{Float64}}, Tuple{}, Tuple{Vector{Float64}}}, sols::Vector{Any})
    from 
    ModelingToolkit → sccnonlinearproblem.jl:8
    #_#1116(sys::ModelingToolkit.System, op::Dict{…}; eval_expression::Bool, eval_module::Module, cse::Bool, u0_constructor::Function, kwargs::@Kwargs{…}) [...show types...](http://localhost:1234/edit?id=3966e1e0-88b4-11f0-1f03-e14f160c0b7a#)
    from 
    ModelingToolkit → sccnonlinearproblem.jl:269
    ModelingToolkit.InitializationProblem{true, SciMLBase.FullSpecialize}(sys::ModelingToolkit.System, t::Float64, op::Dict{Any, Any}; guesses::Dict{Any, Any}, check_length::Bool, warn_initialize_determined::Bool, initialization_eqs::Vector{Any}, fully_determined::Nothing, check_units::Bool, use_scc::Bool, allow_incomplete::Bool, algebraic_only::Bool, time_dependent_init::Bool, kwargs::@Kwargs{u0_constructor::typeof(identity), p_constructor::typeof(identity), eval_expression::Bool, eval_module::Module, warn_cyclic_dependency::Bool, circular_dependency_max_cycle_length::Int64, circular_dependency_max_cycles::Int64})
    from 
    ModelingToolkit → initializationproblem.jl:138
    InitializationProblem
    from 
    initializationproblem.jl:20
    #_#1098
    from 
    maybe_build_initialization_problem(sys::ModelingToolkit.System, iip::Bool, op::Dict{Any, Any}, t::Float64, defs::Dict{Any, Any}, guesses::Dict{Any, Any}, missing_unknowns::Set{Any}; implicit_dae::Bool, time_dependent_init::Bool, u0_constructor::Function, p_constructor::Function, floatT::Type, initialization_eqs::Vector{Any}, use_scc::Bool, kwargs::@Kwargs{warn_initialize_determined::Bool, eval_expression::Bool, eval_module::Module, fully_determined::Nothing, warn_cyclic_dependency::Bool, check_units::Bool, circular_dependency_max_cycle_length::Int64, circular_dependency_max_cycles::Int64, algebraic_only::Bool, allow_incomplete::Bool})
    from 
    ModelingToolkit → problem_utils.jl:1118
    process_SciMLProblem(constructor::Type, sys::ModelingToolkit.System, op::OrderedCollections.OrderedDict{Any, Any}; build_initializeprob::Bool, implicit_dae::Bool, t::Float64, guesses::Dict{Any, Any}, warn_initialize_determined::Bool, initialization_eqs::Vector{Any}, eval_expression::Bool, eval_module::Module, fully_determined::Nothing, check_initialization_units::Bool, u0_eltype::Nothing, tofloat::Bool, u0_constructor::typeof(identity), p_constructor::typeof(identity), check_length::Bool, symbolic_u0::Bool, warn_cyclic_dependency::Bool, circular_dependency_max_cycle_length::Int64, circular_dependency_max_cycles::Int64, substitution_limit::Int64, use_scc::Bool, time_dependent_init::Bool, algebraic_only::Bool, allow_incomplete::Bool, is_initializeprob::Bool, kwargs::@Kwargs{expression::DataType, check_compatibility::Bool})
    from 
    ModelingToolkit → problem_utils.jl:1382
    (SciMLBase.ODEProblem{true, SciMLBase.FullSpecialize})(sys::ModelingToolkit.System, op::OrderedCollections.OrderedDict{Any, Any}, tspan::Tuple{Float64, Float64}; callback::Nothing, check_length::Bool, eval_expression::Bool, expression::Type, eval_module::Module, check_compatibility::Bool, kwargs::@Kwargs{})
    from 
    ModelingToolkit → odeproblem.jl:81
    ODEProblem
    from 
    odeproblem.jl:73
    ODEProblem
    from 
    ODEProblem
    from 
    macro expansion
    from 
    timing.jl:581
    from 
    [This cell: line 1](http://localhost:1234/edit?id=3966e1e0-88b4-11f0-1f03-e14f160c0b7a#e8b778b9-f27f-485b-b342-d27707e0292a)

    @time "body_prop: " body_prop = ODEProblem(body_sys, body_sys_op, (0.0, 1.0)); #; guesses=guess_dict);

Environment (please complete the following information):

• Output of using Pkg; Pkg.status()

  Activating project at `C:\Users\  ...  \Notebooks_MTK\Env_MTK10`
Status `C:\Users\  ...  \Notebooks_MTK\Env_MTK10\Project.toml`
  [35d6a980] ColorSchemes v3.30.0
  [5ae59095] Colors v0.13.1
  [e084ae63] CoolProp v0.2.1
  [a93c6f00] DataFrames v1.7.1
  [82cc6244] DataInterpolations v8.6.0
⌅ [864edb3b] DataStructures v0.18.22
  [0c46a032] DifferentialEquations v7.16.1
  [f6369f11] ForwardDiff v1.1.0
  [f7f18e0c] GLFW v3.4.5
  [e9467ef8] GLMakie v0.13.6
  [5c1252a2] GeometryBasics v0.5.10
  [b964fa9f] LaTeXStrings v1.4.0
  [961ee093] ModelingToolkit v10.21.0
  [16a59e39] ModelingToolkitStandardLibrary v2.25.0
  [510215fc] Observables v0.5.5
  [1dea7af3] OrdinaryDiffEq v6.102.0
  [127b3ac7] OrdinaryDiffEqNonlinearSolve v1.14.1
  [91a5bcdd] Plots v1.40.19
  [7f904dfe] PlutoUI v0.7.71
  [94ee1d12] Quaternions v0.7.6
  [f2b01f46] Roots v2.2.10
  [6038ab10] Rotations v1.7.1
  [0bca4576] SciMLBase v2.116.1
  [5c889d49] SkewLinearAlgebra v1.0.0
  [90137ffa] StaticArrays v1.9.15
  [10745b16] Statistics v1.11.1
  [1986cc42] Unitful v1.24.0
  [45397f5d] UnitfulLatexify v1.7.0
  [de0858da] Printf v1.11.0
Info Packages marked with ⌅ have new versions available but compatibility constraints restrict them from upgrading. To see why use `status --outdated`

• Output of using Pkg; Pkg.status(outdated=true; mode = PKGMODE_MANIFEST)

Status `C:\Users\robur\OneDrive\Documents\Projects\pluto_notebooks\Notebooks_MTK\Env_MTK10\Manifest.toml`
⌅ [861a8166] Combinatorics v1.0.2 (<v1.0.3): SymbolicUtils
⌅ [864edb3b] DataStructures v0.18.22 (<v0.19.1): ModelingToolkit, MultivariatePolynomials, OrdinaryDiffEqCore, StochasticDiffEq, Sundials
⌅ [8fc22ac5] FilePaths v0.8.3 (<v0.9.0): Makie
⌅ [d1acc4aa] IntervalArithmetic v0.22.36 (<v0.23.0): ExactPredicates
⌅ [70703baa] JuliaSyntax v0.4.10 (<v1.0.2): JuliaFormatter
⌃ [7ed4a6bd] LinearSolve v3.28.0 (<v3.39.2)
⌃ [102ac46a] MultivariatePolynomials v0.5.9 (<v0.5.10)
⌅ [aea7be01] PrecompileTools v1.2.1 (<v1.3.3): julia
⌅ [08abe8d2] PrettyTables v2.4.0 (<v3.0.8): DataFrames, DataInterpolations
⌅ [3351c21f] CoolProp_jll v6.8.0+0 (<v7.0.0+0): CoolProp
⌅ [b22a6f82] FFMPEG_jll v6.1.3+0 (<v7.1.1+0): Makie
⌅ [30392449] Pixman_jll v0.44.2+0 (<v0.46.2+0): Cairo_jll
⌅ [fb77eaff] Sundials_jll v5.2.3+0 (<v7.4.1+0): Sundials

• Output of versioninfo()

Julia Version 1.11.6
Commit 9615af0f26 (2025-07-09 12:58 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 8 × Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, skylake)
Threads: 4 default, 0 interactive, 2 GC (on 8 virtual cores)
Environment:
  JULIA_REVISE_WORKER_ONLY = 1

Additional context

Add any other context about the problem here.

[RobbesU]

Downgraded to 10.19 and that also throws the error.
Currently breaking out the System so I can put directly in a representative MWE.

[ChrisRackauckas]

Can you share the pluto notebook? This is odd, view should never be called on those things

[RobbesU]

Notebook at https://gist.github.com/RobbesU/1cc3a3f15ddb58cb0f0fd425ede7038f
I just double checked: it works fine under 10.17, but throws the error under 10.19 and 10.21. 10.18 and 10.20 not checked.

[AayushSabharwal]

That's certainly an... interesting error.

[RobbesU]

I've removed all external forces etc and simplified the system right down to a 'dumb' mass-spring-mass without any other interactions. Problem persists.
Simplified system file at https://gist.github.com/RobbesU/45c1e367a69688c8a449992499d9e85f

[RobbesU]

Tested w MTK v10.18.0 and also has the problem, so appears to have been introduced in 10.18.0

[RobbesU]

Managed to pin down the error source in my model: It sits in providing ωb as an initial condition in guesses vs in parameters p.
ω = R ωb where R is a 3x3 rotation matrix function.
MTK 10.17- accepts ωb as a guess with an initial value for ω, 18+ requires ωb provided as firm initial value in p.
But why it then throws a 'view' Error ???

This FAILS under 10.18+

body_sys_u0 = OrderedDict(
            ...
             :body1₊ω => [0.,0.,0.],       # Providing ωb variable as guess FAILS under MTK 10.18+ but works under 17-
             :body2₊ω => [0.,0.,0.],
					)
guess_dict = OrderedDict(
             ...
             :body1₊ωb => [0.,0.,0.],       # Providing ωb variable as guess FAILS under MTK 10.18+ but works under 17-
             :body2₊ωb => [0.,0.,0.],
                                         )

This WORKS under 10.18+

body_sys_u0 = OrderedDict(
             ...
             :body1₊ωb => [0.,0.,0.],    # MTK 10.18+ specifically requires ωb as initial values.
             :body2₊ωb => [0.,0.,0.],
         #    :body1₊ω => [0.,0.,0.],       # not required under 10.18+
         #    :body2₊ω => [0.,0.,0.],
					)
guess_dict = OrderedDict(
             ...
                                         )

This all somehow derives from these equations in component MultiFlangeBody3D()

eqs = [
           ...
		collect( D(ω)  .~ ω̇ )...
		collect( D(ωb) .~ ω̇b )...
		collect( D(α)  .~ ωb )...    # angle derivate from BODY frame
		collect( ω     .~ R* ωb)...
        collect( R .~ rotmat(α...) )...                        # rotmat body in world
          ...
        ]

which gives, both under 10.17- and 10.18+, the exact same system equations

Symbolics.Equation[
    Differential(t)((α(t))[1]) ~ (ωb(t))[1],    #  & [2] & [3]
    Differential(t)((ωb(t))[1]) ~ (ω̇b(t))[1]  #  & [2] & [3]    ω̇b = ω dot b
    ...
    ]

However, defining the MultiFlangeBody3D() by itself as a System then the associated ODEProblem quite happily accepts ω in p and ωb in guesses, so the error appears to creep in when this MultiFlanceBody3D component is used inside the larger system.

Digging further to try pin point origin

[RobbesU]

Having dug deeper again, I think that possibly the root cause at model level from v10.18 lies at me having provided an initial condition for unknown ωb as a guess, which was acceptable and resolved until v10.18.
In that case, the remaining issue then the type of error it throws rather than the fact that it throws an error.
Maybe a solution is to provide a "value must be provided as u0 not as guess" error message before it throws the view error?

Here's the most basic MWE I can create to kind-of replicate the issue (although it doesn't throw the view error but Cyclic guesses detected error)

using ModelingToolkit          # reexports e.g. Symbolics
using DifferentialEquations
using StaticArrays
using LinearAlgebra: LinearAlgebra as LA

#-------------------------------------------------
function rotmat(α1::Real,α2::Real,α3::Real)
	c1, s1 = cos(α1), sin(α1)
    c2, s2 = cos(α2), sin(α2)
    c3, s3 = cos(α3), sin(α3)
    rotx = @MMatrix [1 0 0; 
                     0 c1 -s1;
                     0 s1  c1] 
    roty = @MMatrix [ c2 0 s2;
                      0  1 0;
                     -s2 0 c2]
    rotz = @MMatrix [c3 -s3 0; #
                     s3  c3 0;
                      0   0 1] 
	 rotz * roty * rotx
end

#-------------------------------------------------
@component function MWE_Body3D(;name, Ib=[1. 0 0; 0 1. 0; 0 0 1.], p0=[0.,0.,0.]) 
	pars =  @parameters begin
		# params symbolised here can be set/changed in the p0 vector of the Problem initialisation
		Ib[1:3, 1:3] = Ib
		p0[1:3] = p0
	end
    vars = @variables begin
		# any variables initiated here can NOT then be initiated in u0 in ODEProblem()
		α(t)[1:3],   		[description = "World frame Angles in [rad] along world X,Y,Z"]
        ωb(t)[1:3],   		[description = "Body frame Angular velocities in [rad/s] along body X,Y,Z axes"]
	    ω(t)[1:3],   		
		ω̇b(t)[1:3],         [description = "Body frame Angular acceleration in [rad/s²] along body X,Y,Z axes"]
		R(t)[1:3, 1:3],     [description = "Euler angle rotation matrix Body to World frame"]
		p(t)[1:3]
    end
    eqs = [    
		collect( D(α) .~ ω )...
		collect( D(ωb) .~ ω̇b )...
		collect( ω .~ R*ωb)...
		collect( R .~ rotmat(α...) )...                        # rotmat body in world
		collect( ω̇b .~ inv(Ib) * ( transpose(R)*p .- LA.cross(ωb, Ib * ωb)) )...  # acc in body
		collect( p .~ p0)...
	 ]
	@named body_sys = ODESystem(eqs, t, vars, pars; name) #,systems) #, initialization_eqs)
end

#-------------------------------------------------
@named mwe_raw = MWE_Body3D();
mwe_sys = mtkcompile(mwe_raw );

#-------------------------------------------------
mwe_op = Dict(
				:v  => [0.,0.,0.], 
				:α  => [0.,0.,0.],
				#:ωb => [0.,0.,0.0],  # Failure to provide ωb HERE results in "Cyclic guesses detected in the system."
				:p0 => [0.,1,0]
			)

mwe_guesses = Dict( 
					#:ω => [0.,0.,0.], 
					#:ωb => [0.,0.,0.],  # no good providing ωb  as a guess anymore from 10.18 (was fine to 10.17)
			 )

Without providing ωb in mwe_op from 10.18+ results in a

Cyclic guesses detected in the system. Symbolic values were found for the following variables/parameters in the map: 
(ωb(t))[2]  => (ωb(t))[2]
(ωb(t))[1]  => (ωb(t))[1]
(ωb(t))[3]  => (ωb(t))[3]

Could it be that, from 10.18, it throws a view error in the larger system because, with ω instead of ωb provided, it tries to resolve ωb using (along the way) the parameters Ib and p which are both of type view:
mwe_sol.ps[mwe_sys.Ib] = 3×3 view(::Vector{Float64}, [1 4 7; 2 5 8; 3 6 9]) with eltype Float64:
mwe_sol.ps[mwe_sys.p0] = view(::Vector{Float64@, 10:12):

[KonstantinDege]

I get a similar issue with a PlanarMechanic Model but even without any guesses in the system only initial constraints

1-element ExceptionStack:
MethodError: no method matching view(::SciMLBase.LinearProblem{Vector{Float64}, true, Matrix{Float64}, Vector{Float64}, ModelingToolkit.MTKParameters{Vector{Float64}, StaticArraysCore.SizedVector{0, Float64, Vector{Float64}}, Tuple{}, Tuple{}, Tuple{}, Tuple{Vector{Float64}}}, SciMLBase.SymbolicLinearInterface{ModelingToolkit.GeneratedFunctionWrapper{(1, 1, true), RuntimeGeneratedFunctions.RuntimeGeneratedFunction{(:mtkparameters,), ModelingToolkit.var"#_RGF_ModTag", ModelingToolkit.var"#_RGF_ModTag", (0xeff9da89, 0xf79e26a4, 0xad122556, 0x51451bd0, 0x32b4e768), Nothing}, RuntimeGeneratedFunctions.RuntimeGeneratedFunction{(:ˍ₋out, :mtkparameters), ModelingToolkit.var"#_RGF_ModTag", ModelingToolkit.var"#_RGF_ModTag", (0xe42d3c02, 0xde2fb94c, 0x2db93dfd, 0xd79f211d, 0xe7d49859), Nothing}}, ModelingToolkit.GeneratedFunctionWrapper{(1, 1, true), RuntimeGeneratedFunctions.RuntimeGeneratedFunction{(:mtkparameters,), ModelingToolkit.var"#_RGF_ModTag", ModelingToolkit.var"#_RGF_ModTag", (0xe7b7e8fd, 0x44eb25ec, 0x6cb9f0a1, 0xd78cd7f7, 0xd0def729), Nothing}, RuntimeGeneratedFunctions.RuntimeGeneratedFunction{(:ˍ₋out, :mtkparameters), ModelingToolkit.var"#_RGF_ModTag", ModelingToolkit.var"#_RGF_ModTag", (0x9c462e26, 0x3ae12dfb, 0x4335d23a, 0x4aca1e72, 0xe99f55da), Nothing}}, ModelingToolkit.System, ModelingToolkit.ObservedFunctionCache{ModelingToolkit.System}, Nothing}, Base.Pairs{Symbol, Union{}, Tuple{}, @NamedTuple{}}}, ::StaticArraysCore.SVector{2, Int64})
The function view exists, but no method is defined for this combination of argument types.

the interesting thing is my quick prototyp without any fancy inheritence and additional variables worked perfectly fine, even with guesses and so on

but it also being caused by 10.18