Issues

• generate_control_function does not pass options of the structural simplification (reassemble_alg) to mtkcompile

  SciML/ModelingToolkit.jl#5255 · Filter by author baggepinnen opened on Oct 4, 2026

• linearize: the input Jacobians are evaluated at the guess of an input that the initialization solves for

  SciML/ModelingToolkit.jl#5224 · Filter by author baggepinnen opened on Sep 29, 2026
  1

• Stream connectors: positivemax drops sq, so outer-connector stream mixing is unweighted

  SciML/ModelingToolkit.jl#5218 · Filter by author ChrisRackauckas-Claude opened on Sep 27, 2026

• Stream connectors: instream_rt uses the wrong sign for outer-connector weights (NaN in hierarchical connects)

  SciML/ModelingToolkit.jl#5217 · Filter by author ChrisRackauckas-Claude opened on Sep 27, 2026

• InvalidKeyError / MissingParametersError are unreachable: bad keys throw TypeError in build_operating_point first (test/problem_validation.jl fails 5/5, not wired in)

  SciML/ModelingToolkit.jl#5216 · Filter by author ChrisRackauckas-Claude opened on Sep 27, 2026

• Tearing picks a pivot that vanishes at t0 (time-dependent constraint coefficient): NaN initial value, no warning

  SciML/ModelingToolkit.jl#5212 · Filter by author ChrisRackauckas-Claude opened on Sep 26, 2026
  4

• Construct AutoDespecialize ODEProblems in the despecialized form (per-model time-to-first-solve)

  SciML/ModelingToolkit.jl#5211 · Filter by author ChrisRackauckas-Claude opened on Sep 26, 2026

• Allow bindings on indexed array parameter keys

  SciML/ModelingToolkit.jl#5210 · Filter by author Fololo opened on Sep 25, 2026

• Clocked discrete events: no reaction at tspan[2] when it falls on a tick — intended contract? Please document (or expose final_affect)

  SciML/ModelingToolkit.jl#5207 · Filter by author pankgeorg opened on Sep 24, 2026
  

• Discrete event on a system with algebraic equations changes a differential state instead of the algebraic variable

  SciML/ModelingToolkit.jl#5200 · Filter by author ChrisRackauckas-Claude opened on Sep 23, 2026
  1

• Cost gradient fails with 'Differentiation of x[1] inside lazy array expressions' when sum(A*x) is nested in the cost (hash-order dependent)

  SciML/ModelingToolkit.jl#5199 · Filter by author ChrisRackauckas-Claude opened on Sep 23, 2026

• Fails to solve SteadyStateProblem

  bug
  SciML/ModelingToolkit.jl#5194 · Filter by author wenflo opened on Sep 23, 2026

• DAEProblem: accept derivative guesses instead of requiring every du0 in op, so MTK initialization can find consistent du0

  SciML/ModelingToolkit.jl#5193 · Filter by author ChrisRackauckas-Claude opened on Sep 23, 2026
  2

• No derivative rule for instream_rt: jac = true fails with Float64(::Num) on multi-source stream connections

  SciML/ModelingToolkit.jl#5192 · Filter by author ChrisRackauckas-Claude opened on Sep 23, 2026
  1

• Initialization fails for residual-form equations over array slices (Differential(t) with independent variable nothing)

  SciML/ModelingToolkit.jl#5188 · Filter by author ChrisRackauckas-Claude opened on Sep 23, 2026
  1

• varmap_to_vars is quadratic in the element count of array unknowns (DAEProblem construction)

  SciML/ModelingToolkit.jl#5187 · Filter by author ChrisRackauckas-Claude opened on Sep 23, 2026
  1

• SCC solve of algebraic System with independent variable indexes parameter tuple out of bounds

  SciML/ModelingToolkit.jl#5174 · Filter by author ChrisRackauckas-Claude opened on Sep 21, 2026
  1

• Linearizing a model that contains discrete callbacks (synchronous / clocked subsystems)

  SciML/ModelingToolkit.jl#5166 · Filter by author baggepinnen opened on Sep 18, 2026

• Emit MultiObjectiveOptimizationFunction for Systems with several costs

  SciML/ModelingToolkit.jl#5150 · Filter by author ChrisRackauckas-Claude opened on Sep 13, 2026
  1

• Compile and generate code for whole-array equation models without scalarizing per element (tracking)

  bot-generatedneeds-chris-review
  SciML/ModelingToolkit.jl#5139 · Filter by author ChrisRackauckas opened on Sep 13, 2026
  1

• Array parameter defaults and bindings given as slices of another array parameter fail in MTKParameters

  bot-generatedneeds-chris-review
  SciML/ModelingToolkit.jl#5138 · Filter by author ChrisRackauckas opened on Sep 13, 2026

• Flaky: downgrade Initialization use_scc = true gradient test returns 1e153 (Dual solve goes non-finite at t=0)

  SciML/ModelingToolkit.jl#5125 · Filter by author ChrisRackauckas-Claude opened on Sep 12, 2026
  1

• Preserve array flow balances when expanding ordinary connector connections

  bot-generatedneeds-chris-review
  SciML/ModelingToolkit.jl#5119 · Filter by author ChrisRackauckas opened on Sep 12, 2026
  1

• Unit validation crashes on causal variable connect: unknowns(::BasicSymbolic) MethodError in MTKDynamicQuantitiesExt

  SciML/ModelingToolkit.jl#5118 · Filter by author ChrisRackauckas-Claude opened on Sep 12, 2026
  1

• Preserve array derivatives in implicit DAE residual code generation

  bot-generatedneeds-chris-review
  SciML/ModelingToolkit.jl#5097 · Filter by author ChrisRackauckas opened on Sep 9, 2026
  1