# WARNING: Detected access to binding XXX in a world prior to its definition world

**URL:** <https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273>\
**Category:** General Usage\
**Created:** [January 26, 2026, 1:52pm UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273 "2026-01-26T13:52:05Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![tomtom](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tomtom/32/5106_2.png) [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Post date:** [January 26, 2026, 1:52pm UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/1 "2026-01-26T13:52:05Z")

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suddenly as of today (1/26/26) I got a lot of warnings as in the title when launching Julia. Nothing updated, why??? How to avoid those warning? Using 1.12.3

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**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [January 26, 2026, 7:45pm UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/2 "2026-01-26T19:45:44Z")

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You could downgrade to Julia 1.11. Then these warnings will disappear.

If you want to debug why they appear, please share the output of:

```julia-auto
using Pkg
Pkg.status()

```

It is possible that one of your (newly installed) packages is causing these warnings.

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<div class="post-metadata">

**Author:** ![tomtom](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tomtom/32/5106_2.png) [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Post date:** [January 27, 2026, 3:03am UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/3 "2026-01-27T03:03:44Z")

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actually those warnings seem to appear after I installed `MLJ` and `MLJDecisionTreeInterface`

```julia-auto
julia> Pkg.status()
Status `~/.julia/environments/v1.12/Project.toml`
  [6e4b80f9] BenchmarkTools v1.6.3
  [336ed68f] CSV v0.10.15
  [81a5f4ea] CatViews v1.0.0
  [324d7699] CategoricalArrays v1.0.2
  [aaaa29a8] Clustering v0.15.8
  [da1fd8a2] CodeTracking v3.0.0
  [8a292aeb] Cuba v2.3.0
  [a93c6f00] DataFrames v1.8.1
  [31a5f54b] Debugger v0.7.16
  [7806a523] DecisionTree v0.12.4
  [b4f34e82] Distances v0.10.12
  [31c24e10] Distributions v0.25.123
  [497a8b3b] DoubleFloats v1.5.0
  [fa6b7ba4] DualNumbers v0.6.9
  [38e38edf] GLM v1.9.2
  [708ec375] Gumbo v0.8.3
  [19dc6840] HCubature v1.8.0
  [cd3eb016] HTTP v1.10.19
  [50ceba7f] HyperDualNumbers v4.0.10
  [033835bb] JLD2 v0.6.3
  [84687f94] JLD2Bzip2 v0.1.1
  [49ca2578] JLD2Lz4 v0.1.1
⌅ [682c06a0] JSON v0.21.4
  [add582a8] MLJ v0.22.0
  [c6f25543] MLJDecisionTreeInterface v0.4.3
  [429524aa] Optim v2.0.0
  [90014a1f] PDMats v0.11.37
  [91a5bcdd] Plots v1.41.4
  [295af30f] Revise v3.13.1
  [6ef1bc8b] Scanf v0.5.4
  [aed68c70] SkipNan v0.2.0
  [276daf66] SpecialFunctions v2.6.1
  [90137ffa] StaticArrays v1.9.16
  [2913bbd2] StatsBase v0.34.10
  [f269a46b] TimeZones v1.22.2
  [a759f4b9] TimerOutputs v0.5.29
Info Packages marked with ⌅ have new versions available but compatibility constraints restrict them from upgrading. To see why use `status --outdated`

```

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<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [January 27, 2026, 3:29am UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/4 "2026-01-27T03:29:38Z")

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> [@tomtom](#):
>
> `MLJDecisionTreeInterface`

So perhaps file a bug in MLJ.jl or MLJDecisionTreeInterface.jl ?

But that would require that you come up with a minimal example that triggers this issue.

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<div class="post-metadata">

**Author:** ![tomtom](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tomtom/32/5106_2.png) [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Post date:** [January 27, 2026, 3:59am UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/5 "2026-01-27T03:59:14Z")

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unfortunately the problem persists after removing `MLJ` and `MLJDecisionTreeInterface.jl`…

so, how to do a clean uninstall of Julia? (using juliaup)

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<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [January 27, 2026, 4:06am UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/6 "2026-01-27T04:06:23Z")

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> [@tomtom](#):
>
> how to do a clean uninstall of Julia? (using juliaup)

Why do you want to uninstall Julia?

If you want to switch to Julia 1.11, you can do

```julia-auto
juliaup add 1.11
juliaup default 1.11

```

If you want a completely clean start, you can rename the `.julia` folder.

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<div class="post-metadata">

**Author:** ![tomtom](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tomtom/32/5106_2.png) [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Post date:** [January 27, 2026, 8:57am UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/7 "2026-01-27T08:57:13Z")

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`juliaup update` and subsequent re-precompilation does not help.

At the end, I needed to rm `~/.julia` and add every package manually again to get around…

---

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [January 27, 2026, 9:59am UTC](https://discourse.julialang.org/t/warning-detected-access-to-binding-xxx-in-a-world-prior-to-its-definition-world/135273/8 "2026-01-27T09:59:24Z")

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> [@tomtom](#):
>
> add every package manually again to get around

If you have a well-maintained `Project.toml` file, this is not needed. You can just do:

```julia-auto
using Pkg
Pkg.instantiate()

```

But adding packages one by one manually can be useful for debugging to see if adding a specific package is causing a problem.

Finally:  
Make sure you do

```julia-auto
using Pkg
Pkg.update()

```

now and then. That just updates your packages. `juliaup update` does NOT update any packages, it only updates Julia itself.

And if you have a working configuration, make sure you create a backup copy of your `Manifest.toml` file. I use the command `cp Manifest-v1.12.toml Manifest-v1.12.toml.default` to create a backup and commit the default manifest to git. Then you can always restore the last working set of package versions if something should break after `Pkg.update()`.