BoundsError when get_du is called in init callback with non-FSAL stiff solver (QNDF) #3117
Description
Describe the bug 🐞
Calling get_du(integrator) inside a FunctionCallingCallback with func_start=true during solver initialization crashes for stiff non-FSAL methods (e.g., QNDF). The callback fires before any stages are computed, so get_du tries to interpolate using an empty k array and throws BoundsError.
Expected behavior
get_du should be usable in init callbacks for all solvers: either return f(u,p,t) (or similar) when no stages exist yet, or at least not crash
Minimal Reproducible Example 👇
using SciMLBase: ODEProblem
using OrdinaryDiffEqBDF: QNDF
using OrdinaryDiffEqTsit5: Tsit5
using OrdinaryDiffEqCore: get_du, init, solve!
using DiffEqCallbacks: FunctionCallingCallback
function f!(du, u, p, t)
du[1] = -u[1]
end
function my_callback(u, t, integrator)
du = get_du(integrator)
println(" t=$t, du=$du")
end
u0 = [1.0]
prob = ODEProblem(f!, u0, (0.0, 1.0))
cb = FunctionCallingCallback(my_callback; func_start = true)
println("Tsit5 (FSAL):")
integrator = init(prob, Tsit5(); callback = cb, save_everystep = false)
solve!(integrator)
println("\nQNDF (stiff, non-FSAL):")
integrator = init(prob, QNDF(); callback = cb, save_everystep = false)
solve!(integrator)
Error & Stacktrace
ERROR: LoadError: BoundsError: attempt to access 0-element Vector{Vector{Float64}} at index [1]
Stacktrace:
[1] throw_boundserror
[2] getindex
[3] maybeview
[4] _ode_interpolant! at OrdinaryDiffEqBDF/src/bdf_interpolants.jl:165
[5] ode_interpolant at OrdinaryDiffEqCore/src/dense/generic_dense.jl:1272
[7] current_interpolant at OrdinaryDiffEqCore/src/dense/generic_dense.jl:383
[10] get_du at OrdinaryDiffEqCore/src/integrators/integrator_interface.jl:80
[11] my_callback at models/debug/repro.jl:21
[17] initialize_callbacks! at OrdinaryDiffEqCore/src/solve.jl:932
[18] __init at OrdinaryDiffEqCore/src/solve.jl:715
[19] top-level scope at models/debug/repro.jl:41
Environment (please complete the following information):
- Output of
using Pkg; Pkg.status()
[459566f4] DiffEqCallbacks v4.12.0
[6ad6398a] OrdinaryDiffEqBDF v1.22.0 [loaded: v1.21.0]
[bbf590c4] OrdinaryDiffEqCore v3.15.0 [loaded: v3.10.0]
[b1df2697] OrdinaryDiffEqTsit5 v1.9.0
[0bca4576] SciMLBase v2.148.0 [loaded: v2.145.0]- Output of
using Pkg; Pkg.status(; mode = PKGMODE_MANIFEST)
[47edcb42] ADTypes v1.21.0
[7d9f7c33] Accessors v0.1.43
[79e6a3ab] Adapt v4.5.0 [loaded: v4.4.0]
[4fba245c] ArrayInterface v7.22.0
[62783981] BitTwiddlingConvenienceFunctions v0.1.6
[70df07ce] BracketingNonlinearSolve v1.11.0 [loaded: v1.10.0]
[2a0fbf3d] CPUSummary v0.2.7
[d360d2e6] ChainRulesCore v1.26.0
[fb6a15b2] CloseOpenIntervals v0.1.13
[38540f10] CommonSolve v0.2.6
[bbf7d656] CommonSubexpressions v0.3.1
[f70d9fcc] CommonWorldInvalidations v1.0.0
[34da2185] Compat v4.18.1
[a33af91c] CompositionsBase v0.1.2
[2569d6c7] ConcreteStructs v0.2.3
[187b0558] ConstructionBase v1.6.0
[adafc99b] CpuId v0.3.1
[864edb3b] DataStructures v0.19.3
[2b5f629d] DiffEqBase v6.210.1 [loaded: v6.210.0]
[459566f4] DiffEqCallbacks v4.12.0
[163ba53b] DiffResults v1.1.0
[b552c78f] DiffRules v1.15.1
[a0c0ee7d] DifferentiationInterface v0.7.16
[ffbed154] DocStringExtensions v0.9.5
[4e289a0a] EnumX v1.0.7
[f151be2c] EnzymeCore v0.8.18
[e2ba6199] ExprTools v0.1.10
[55351af7] ExproniconLite v0.10.14
[7034ab61] FastBroadcast v0.3.5
[9aa1b823] FastClosures v0.3.2
[a4df4552] FastPower v1.3.1
[1a297f60] FillArrays v1.16.0
[6a86dc24] FiniteDiff v2.29.0
[f6369f11] ForwardDiff v1.3.2
[069b7b12] FunctionWrappers v1.1.3
[77dc65aa] FunctionWrappersWrappers v0.1.3
[46192b85] GPUArraysCore v0.2.0
[615f187c] IfElse v0.1.1
[3587e190] InverseFunctions v0.1.17
[92d709cd] IrrationalConstants v0.2.6
[82899510] IteratorInterfaceExtensions v1.0.0
[692b3bcd] JLLWrappers v1.7.1
[ae98c720] Jieko v0.2.1
[ba0b0d4f] Krylov v0.10.5
[10f19ff3] LayoutPointers v0.1.17
[87fe0de2] LineSearch v0.1.6
[7ed4a6bd] LinearSolve v3.62.0 [loaded: v3.59.1]
[2ab3a3ac] LogExpFunctions v0.3.29
[e6f89c97] LoggingExtras v1.2.0
[1914dd2f] MacroTools v0.5.16
[d125e4d3] ManualMemory v0.1.8
[bb5d69b7] MaybeInplace v0.1.4
[2e0e35c7] Moshi v0.3.7
[46d2c3a1] MuladdMacro v0.2.4
[77ba4419] NaNMath v1.1.3
[8913a72c] NonlinearSolve v4.16.0
[be0214bd] NonlinearSolveBase v2.15.0 [loaded: v2.14.0]
[5959db7a] NonlinearSolveFirstOrder v2.0.0
[9a2c21bd] NonlinearSolveQuasiNewton v1.12.0
[26075421] NonlinearSolveSpectralMethods v1.6.0
[bac558e1] OrderedCollections v1.8.1
[6ad6398a] OrdinaryDiffEqBDF v1.22.0 [loaded: v1.21.0]
[bbf590c4] OrdinaryDiffEqCore v3.15.0 [loaded: v3.10.0]
[4302a76b] OrdinaryDiffEqDifferentiation v2.2.1 [loaded: v2.1.0]
[127b3ac7] OrdinaryDiffEqNonlinearSolve v1.23.0
[2d112036] OrdinaryDiffEqSDIRK v1.12.0
[b1df2697] OrdinaryDiffEqTsit5 v1.9.0
[f517fe37] Polyester v0.7.19
[1d0040c9] PolyesterWeave v0.2.2
[d236fae5] PreallocationTools v1.1.2
[aea7be01] PrecompileTools v1.3.3
[21216c6a] Preferences v1.5.2
[3cdcf5f2] RecipesBase v1.3.4
[731186ca] RecursiveArrayTools v3.48.0
[189a3867] Reexport v1.2.2
[ae029012] Requires v1.3.1
[7e49a35a] RuntimeGeneratedFunctions v0.5.17
[94e857df] SIMDTypes v0.1.0
[0bca4576] SciMLBase v2.148.0 [loaded: v2.145.0]
[19f34311] SciMLJacobianOperators v0.1.12
[a6db7da4] SciMLLogging v1.9.1
[c0aeaf25] SciMLOperators v1.15.1
[431bcebd] SciMLPublic v1.0.1
[53ae85a6] SciMLStructures v1.10.0
[efcf1570] Setfield v1.1.2
[727e6d20] SimpleNonlinearSolve v2.11.0
[0a514795] SparseMatrixColorings v0.4.24
[276daf66] SpecialFunctions v2.7.1
[aedffcd0] Static v1.3.1
[0d7ed370] StaticArrayInterface v1.9.0
[90137ffa] StaticArrays v1.9.17
[1e83bf80] StaticArraysCore v1.4.4
[10745b16] Statistics v1.11.1
[7792a7ef] StrideArraysCore v0.5.8
[2efcf032] SymbolicIndexingInterface v0.3.46
[8290d209] ThreadingUtilities v0.5.5
[a759f4b9] TimerOutputs v0.5.29
[781d530d] TruncatedStacktraces v1.4.0
[1d5cc7b8] IntelOpenMP_jll v2025.2.0+0
[856f044c] MKL_jll v2025.2.0+0
[efe28fd5] OpenSpecFun_jll v0.5.6+0
[1317d2d5] oneTBB_jll v2022.0.0+1
[0dad84c5] ArgTools v1.1.2
[56f22d72] Artifacts v1.11.0
[2a0f44e3] Base64 v1.11.0
[ade2ca70] Dates v1.11.0
[8ba89e20] Distributed v1.11.0
[f43a241f] Downloads v1.7.0
[7b1f6079] FileWatching v1.11.0
[9fa8497b] Future v1.11.0
[b77e0a4c] InteractiveUtils v1.11.0
[ac6e5ff7] JuliaSyntaxHighlighting v1.12.0
[4af54fe1] LazyArtifacts v1.11.0
[b27032c2] LibCURL v0.6.4
[76f85450] LibGit2 v1.11.0
[8f399da3] Libdl v1.11.0
[37e2e46d] LinearAlgebra v1.12.0
[56ddb016] Logging v1.11.0
[d6f4376e] Markdown v1.11.0
[ca575930] NetworkOptions v1.3.0
[44cfe95a] Pkg v1.12.1
[de0858da] Printf v1.11.0
[9a3f8284] Random v1.11.0
[ea8e919c] SHA v0.7.0
[9e88b42a] Serialization v1.11.0
[6462fe0b] Sockets v1.11.0
[2f01184e] SparseArrays v1.12.0
[f489334b] StyledStrings v1.11.0
[fa267f1f] TOML v1.0.3
[a4e569a6] Tar v1.10.0
[cf7118a7] UUIDs v1.11.0
[4ec0a83e] Unicode v1.11.0
[e66e0078] CompilerSupportLibraries_jll v1.3.0+1
[deac9b47] LibCURL_jll v8.15.0+0
[e37daf67] LibGit2_jll v1.9.0+0
[29816b5a] LibSSH2_jll v1.11.3+1
[14a3606d] MozillaCACerts_jll v2025.11.4
[4536629a] OpenBLAS_jll v0.3.29+0
[05823500] OpenLibm_jll v0.8.7+0
[458c3c95] OpenSSL_jll v3.5.4+0
[bea87d4a] SuiteSparse_jll v7.8.3+2
[83775a58] Zlib_jll v1.3.1+2
[8e850b90] libblastrampoline_jll v5.15.0+0
[8e850ede] nghttp2_jll v1.64.0+1
[3f19e933] p7zip_jll v17.7.0+0- Output of
versioninfo()
Julia Version 1.12.5
Commit 5fe89b8ddc1 (2026-02-09 16:05 UTC)
Build Info:
Official https://julialang.org release
Platform Info:
OS: macOS (arm64-apple-darwin24.0.0)
CPU: 14 × Apple M4 Pro
WORD_SIZE: 64
LLVM: libLLVM-18.1.7 (ORCJIT, apple-m4)
GC: Built with stock GC
Threads: 10 default, 1 interactive, 10 GC (on 10 virtual cores)
Environment:
JULIA_EDITOR = code
JULIA_VSCODE_REPL = 1Additional context
We walked into this crash after updating manifest. In earlier versions this code would not crash but follow the the expected behaviour as described.