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

General Usage
1

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

2

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:

using Pkg
Pkg.status()

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

3

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

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 To see why use `status --outdated`
4

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.

5

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

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

6

Why do you want to uninstall Julia?

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

juliaup add 1.11
juliaup default 1.11

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

7

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…

8

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

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

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().

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