# Long stack trace, identify precise error location
**URL:** https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285
**Category:** General Usage
**Created:** [May 3, 2023, 11:09pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285 "2023-05-03T23:09:50Z")
**Posts on this page:** 18
**Page:** 1
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 3, 2023, 11:09pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/1 "2023-05-03T23:09:50Z")
I am trying to solve a UODE where the neural network uses a tensor-basis neural net. Here are the first few lines of my stack trace (the details are not important since I am not asking you to debug my code 馃檪 ):
```julia
ERROR: MethodError: no method matching init(::Nothing, ::Tsit5{typeof(OrdinaryDiffEq.trivial_limiter!), typeof(OrdinaryDiffEq.trivial_limiter!), Static.False}; sensealg::InterpolatingAdjoint{0, true, Val{:central}, ReverseDiffVJP{true}}, saveat::Float64)
Closest candidates are:
init(::OptimizationProblem, ::Any, ::Any...; kwargs...)
@ SciMLBase ~/.julia/packages/SciMLBase/VdcHg/src/solve.jl:146
init(::PDEProblem, ::SciMLBase.AbstractDEAlgorithm, ::Any...; kwargs...)
@ DiffEqBase ~/.julia/packages/DiffEqBase/ihYDa/src/solve.jl:1011
init(::SciMLBase.AbstractJumpProblem, ::Any...; kwargs...)
@ DiffEqBase ~/.julia/packages/DiffEqBase/ihYDa/src/solve.jl:441
...
Stacktrace:
[1] macro expansion
@ ~/.julia/packages/Zygote/SuKWp/src/compiler/interface2.jl:0 [inlined]
[2] _pullback(::Zygote.Context{false}, ::typeof(Core.kwcall), ::NamedTuple{(:sensealg, :saveat), Tuple{InterpolatingAdjoint{0, true, Val{:central}, ReverseDiffVJP{true}}, Float64}}, ::typeof(init), ::Nothing, ::Tsit5{typeof(OrdinaryDiffEq.trivial_limiter!), typeof(OrdinaryDiffEq.trivial_limiter!), Static.False})
@ Zygote ~/.julia/packages/Zygote/SuKWp/src/compiler/interface2.jl:9
[3] _apply(::Function, ::Vararg{Any})
@ Core ./boot.jl:838
```
The first line is clear enough:
```julia
ERROR: MethodError: no method matching init(::Nothing, ::Tsit5{typeof(OrdinaryDiffEq.trivial_limiter!), typeof(OrdinaryDiffEq.trivial_limiter!), Static.False}; sensealg::InterpolatingAdjoint{0, true, Val{:central}, ReverseDiffVJP{true}}, saveat::Float64)
```
I followed the very long trace, and I did not find the specific line where this function was executed, and therefore, the error is hard to fix. Given the very long trace, it is hard to believe that this line is not available to the stack trace.
Perhaps there is too much inlining going on. Is it possible to run Julia from the command line with options such that inlining is disabled? That might help. Thanks.
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [May 3, 2023, 11:50pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/2 "2023-05-03T23:50:27Z")
Hard to tell without any code, but it sounds like you did `solve(nothing, Tsit5())` somewhere instead of passing an ODEProblem?
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 3, 2023, 11:52pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/3 "2023-05-03T23:52:45Z")
Of course, what you say is logical, but if it is the case, it is not obvious at all. That is the problem with using high-level interface. The error is happening somewhere within my Ensemble functions. To solve the problem, you鈥檇 have to see the entire code, but I should create a MWE, which again, will take time. I have decided to learn how to use `Debugging.jl`.
---
### Author:  [@hendri54](https://discourse.julialang.org/u/hendri54)
#### Post date: [May 4, 2023, 12:41pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/4 "2023-05-04T12:41:07Z")
Perhaps relevant: There are several packages, such as [RelevanceStrackTraces.jl](https://github.com/Cvikli/RelevanceStacktrace.jl) that are designed to make it easier to find the place in the user code that caused the exception to be thrown.
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 4, 2023, 2:39pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/5 "2023-05-04T14:39:34Z")
Thank you. I had not heard of this. Of course, I鈥檒l try it out.
So far, I have been unsuccessful in my attempts to use Debugger.jl.
---
### Author:  [@hendri54](https://discourse.julialang.org/u/hendri54)
#### Post date: [May 4, 2023, 3:49pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/6 "2023-05-04T15:49:25Z")
What I generally do in cases of deeply nested calls is to find the first item in the stacktrace where one of my functions occurs. `RelevanceStrackTraces` is designed to point to that place clearly.
Then I insert an `@assert !isnothing(x)` type of statement there (which I just keep unless the code is really performance critical). Then I work my way backwards through the stacktrace.
I have not had much luck with the debugger, but I rarely miss it.
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 4, 2023, 6:12pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/7 "2023-05-04T18:12:04Z")
I have a question. When getting a stack trace that starts of as:
```julia
ERROR: MethodError: no method matching (::Chain{Tuple{Dense{typeof(tanh), Matrix{Float32}, 鈥, Dense{typeof(identity), Matrix{Float32}, 鈥}})(::Vector{Float64}, ::Vector{Float32})
Closest candidates are:
(::Chain)(::Any)
@ Flux ~/.julia/packages/Flux/FWgS0/src/layers/basic.jl:51
Stacktrace:
[1] tbnn_opt(蟽::Matrix{Float32}, D::SMatrix{3, 3, Float64, 9}, model_weights::Vector{Float32}, model_univ::Chain{Tuple{Dense{typeof(tanh), Matrix{Float32}, 鈥, Dense{typeof(identity), Matrix{Float32}, 鈥}}, t::Float32)
@ Main ~/src/2022/rude/giesekus/GE_rude.jl/alex_report_code_2023-03-24/julia19/rude_giesekus_optimized_reduced_scalar.jl:67
[2] dudt_univ_opt!(
```
would it be hard to provide the line number and file that generated the error starting with
```julia
ERROR: MethodError: no method matching (::Chain{Tuple{Dense{typeof(tanh), Matrix{Float32}, 鈥, Dense{typeof(identity), Matrix{Float32}, 鈥}})(::Vector{Float64}, ::Vector{Float32})
```
Why can鈥檛 the information be provided on the very same line together with a link. Isn鈥檛 this information available? I still have not figured out which function generated my original message let alone this one. Thanks.
---
### Author:  [@joa-quim](https://discourse.julialang.org/u/joa-quim)
#### Post date: [May 4, 2023, 6:22pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/8 "2023-05-04T18:22:56Z")
I fee your pain with the inscrutable stack traces.
The debugger is simple to use (not saying it鈥檚 very good) from Visual Studio Code. Just do
`@run your_command` and it will stop somewhere, than you can follow the stacktrace on the left side till you find the point where the error originated.
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 4, 2023, 6:31pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/9 "2023-05-04T18:31:39Z")
@run does not work in REPL.
I love Julia, but it is not written with ease of use in mind. I absolutely do not understand why Julia does not have built in options to manipulate the stack traces in useful ways. Even the long traces shouldn鈥檛 be the default. The original error should clearly state what file and what line it occurred (or a range of lines). Sorry for the rant.
---
### Author:  [@ToucheSir](https://discourse.julialang.org/u/ToucheSir)
#### Post date: [May 4, 2023, 6:39pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/10 "2023-05-04T18:39:36Z")
Maybe I鈥檓 misunderstanding your question, but isn鈥檛 this what
> [@erlebach](#):
>
> ```julia
> [1] tbnn_opt(蟽::Matrix{Float32}, D::SMatrix{3, 3, Float64, 9}, model_weights::Vector{Float32}, model_univ::Chain{Tuple{Dense{typeof(tanh), Matrix{Float32}, 鈥, Dense{typeof(identity), Matrix{Float32}, 鈥}}, t::Float32)
> @ Main ~/src/2022/rude/giesekus/GE_rude.jl/alex_report_code_2023-03-24/julia19/rude_giesekus_optimized_reduced_scalar.jl:67
>
> ```
is showing? The second line starting with `@` there shows (in order) the module, file name and line number on which the error occurred.
---
### Author:  [@joa-quim](https://discourse.julialang.org/u/joa-quim)
#### Post date: [May 4, 2023, 6:46pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/11 "2023-05-04T18:46:26Z")
> [@erlebach](#):
>
> @run does not work in REPL.
I said from Visual Studio Code (it鈥檚 own REPL). But it does also from the normal REPL if you install `Debugger` package, though I鈥檝e no experience with it.
---
### Author:  [@adienes](https://discourse.julialang.org/u/adienes)
#### Post date: [May 4, 2023, 6:47pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/12 "2023-05-04T18:47:11Z")
the debugger is indeed simple to _attempt_ to use, but as far as my experience attempting goes, it doesn鈥檛 work particularly well (to the extent where I end up just returning to `print` debugging)
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 4, 2023, 7:05pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/13 "2023-05-04T19:05:12Z")
@TouchSir,
No. The line that says tbnn is one of my function calls. There is no reference to Chain on that line.
---
### Author:  [@ToucheSir](https://discourse.julialang.org/u/ToucheSir)
#### Post date: [May 4, 2023, 7:17pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/14 "2023-05-04T19:17:23Z")
Oh I see. So that line is actually part of the MethodError error message and not the stacktrace, though I can see why it might be confusing if you鈥檙e not familiar with the error format.
How to interpret this is that at `rude_giesekus_optimized_reduced_scalar.jl:67`, `tbnn_opt` calls a `Chain` struct. You should be able to confirm that by looking at the line in question. ` no method matching (::Chain{Tuple{Dense{typeof(tanh), Matrix{Float32}, 鈥, Dense{typeof(identity), Matrix{Float32}, 鈥}})(::Vector{Float64}, ::Vector{Float32})` looks intimidating, but that鈥檚 mostly because the type parameters take up a lot of space. If we remove them, that line becomes `no method matching (::Chain)(::Vector{Float64}, ::Vector{Float32})`.
As you can tell, `Flux.Chain` only accepts one argument when called, so something is erroneously passing two. The MethodError message tries to help here by referencing `(::Chain)(::Any)` (note one arg only) and linking to its definition [here](https://github.com/FluxML/Flux.jl/blob/v0.13.15/src/layers/basic.jl#L51) so you can investigate further.
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 4, 2023, 8:03pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/15 "2023-05-04T20:03:52Z")
Thanks for the feedback. I do know how to interpret a trace, or thought I did. Concerning Chain and the fact that it has only one argument, I beg to differ. Running `methods Flux.Chain`, I get the result:
```julia
methods(Flux.Chain)
# 3 methods for type constructor:
[1] Chain(; kw...)
@ ~/.julia/packages/Flux/FWgS0/src/layers/basic.jl:40
[2] Chain(layers::T) where T<:Union{Tuple, NamedTuple, AbstractVector}
@ ~/.julia/packages/Flux/FWgS0/src/layers/basic.jl:36
[3] Chain(xs...)
@ ~/.julia/packages/Flux/FWgS0/src/layers/basic.jl:39
```
Doesn鈥檛 the third choice (and even the second) imply that multiple arguments are accepted, contrary to what the error message implies?
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 4, 2023, 8:18pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/16 "2023-05-04T20:18:34Z")
@ToucheSir : Here is some of my code:
```julia
function tbnn_opt(蟽, D, model_weights, model_univ, t)
# Compute elements of the tensor basis
I = SA[1. 0. 0.; 0. 1. 0.; 0. 0. 1.]
# Compute the integrity basis from scalar invariants. Traces.
位 = zeros(1) # must be mutale
位[1] = tr(蟽)
println("input to NN, 位: ", 位)
g = model_univ(位, model_weights) ### Error
F = g[1] .* I
end
# NN model for the nonlinear function F(蟽,纬虈)
model_univ = Flux.Chain(Flux.Dense(1, 8, tanh),
Flux.Dense(8, 1))
p_model, re = Flux.destructure(model_univ)
# Parameters of the linear response (畏0,蟿)
p_system = Float32[1, 1]
```
Yes, I am using Julia 1.9, and so should be using Lux. But surely Flux has not been deprecated, right?
Look at the page: [Built-in Layers 路 Flux](https://fluxml.ai/Flux.jl/stable/models/layers/#Flux.Chain), the stable version of `Flux.jl` . Tons of examples where `Flux.Chain` take multiple arguments. So I still do not undertand the error.
---
### Author:  [@ToucheSir](https://discourse.julialang.org/u/ToucheSir)
#### Post date: [May 4, 2023, 8:35pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/17 "2023-05-04T20:35:40Z")
> [@erlebach](#):
>
> Tons of examples where `Flux.Chain` take multiple arguments. So I still do not undertand the error.
The constructor `mymodel = Chain(layer1, layer2, ...)` takes multiple arguments. _Calling_ that model `mymodel(x)` takes just one. I鈥檓 not sure what `model_weights` and `model_univ` are meant to be in `tbnn_opt` because you generally wouldn鈥檛 separate model structure from weights in Flux, so this seems like a better question for one of the SciML help channels.
> [@erlebach](#):
>
> I am using Julia 1.9, and so should be using Lux. But surely Flux has not been deprecated, right?
This also seems like something specific to only SciML and should likewise be asked there 馃檪
---
### Author:  [@erlebach](https://discourse.julialang.org/u/erlebach)
#### Post date: [May 4, 2023, 8:37pm UTC](https://discourse.julialang.org/t/long-stack-trace-identify-precise-error-location/98285/18 "2023-05-04T20:37:12Z")
Ok, will think some more and do that. I have never posted to specific channels yet.