# CSV.jl fails precompling, TypeError: in Type{...} expression, expected UnionAll, got Type{Parsers.Options}

**URL:** <https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195>\
**Category:** General Usage\
**Tags:** question, csv\
**Created:** [August 27, 2021, 9:32pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195 "2021-08-27T21:32:13Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![erickn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/erickn/32/27431_2.png) [@erickn](https://discourse.julialang.org/u/erickn)\
**Post date:** [August 27, 2021, 9:32pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/1 "2021-08-27T21:32:13Z")

</div>

Hi all,  
Yesterday I found that CSV.jl is failing in precompiling when it is imported in a Jupyter notebook. For testing, it is tried in a new environment only with CSV, but it failed the same way. See below for the error message.  
An intriguing thing is that CSV.jl gets imported and precompiled fine when it is tried in the REPL or a script.  
The version of Julia is Version 1.6.2 on Mac (official one from the Julia website), and CSV.jl v0.8.5 is added using Pkg.  
I wonder what I am doing wrong. Any idea? Thanks!

```julia
using CSV
┌ Info: Precompiling CSV [336ed68f-0bac-5ca0-87d4-7b16caf5d00b]
└ @ Base loading.jl:1342
ERROR: LoadError: LoadError: TypeError: in Type{...} expression, expected UnionAll, got Type{Parsers.Options}
Stacktrace:
  [1] top-level scope
    @ ~/.julia/packages/CSV/Zl2ww/src/detection.jl:164
  [2] include(mod::Module, _path::String)
    @ Base ./Base.jl:386
  [3] include(x::String)
    @ CSV ~/.julia/packages/CSV/Zl2ww/src/CSV.jl:1
  [4] top-level scope
    @ ~/.julia/packages/CSV/Zl2ww/src/CSV.jl:27
  [5] include
    @ ./Base.jl:386 [inlined]
  [6] include_package_for_output(pkg::Base.PkgId, input::String, depot_path::Vector{String}, dl_load_path::Vector{String}, load_path::Vector{String}, concrete_deps::Vector{Pair{Base.PkgId, UInt64}}, source::Nothing)
    @ Base ./loading.jl:1235
  [7] top-level scope
    @ none:1
  [8] eval
    @ ./boot.jl:360 [inlined]
  [9] eval(x::Expr)
    @ Base.MainInclude ./client.jl:446
 [10] top-level scope
    @ none:1
in expression starting at /Users/foo/.julia/packages/CSV/Zl2ww/src/detection.jl:164
in expression starting at /Users/foo/.julia/packages/CSV/Zl2ww/src/CSV.jl:1

Failed to precompile CSV [336ed68f-0bac-5ca0-87d4-7b16caf5d00b] to /Users/foo/.julia/compiled/v1.6/CSV/jl_cgSkrZ.

```

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<div class="post-metadata">

**Author:** ![xiaodai](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xiaodai/32/15937_2.png) [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Post date:** [August 27, 2021, 11:35pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/2 "2021-08-27T23:35:23Z")

</div>

also got the same issue

---

<div class="post-metadata">

**Author:** ![quinnj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/quinnj/32/11_2.png) [@quinnj](https://discourse.julialang.org/u/quinnj)\
**Post date:** [August 29, 2021, 5:54am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/3 "2021-08-29T05:54:42Z")

</div>

This has come up a couple of times recently and is due to a new breaking release in the Parsers.jl v2.0 release, which in and of itself shouldn’t cause problems, since CSV.jl 0.8.5 has dependencies correctly capped, but still becomes an issue because there are unfortunate ways for package dependencies to get loaded without having the right versions. See [this slack thread](https://julialang.slack.com/archives/CBF3Z1D7V/p1628806926093700) for more details. Basically, it boils down to some 3rd-party package (in this case, probably IJulia.jl) loading a package like JSON.jl, which also depends on Parsers.jl, and _does_ have a current release compatible with Parsers.jl 2.0, so 2.0 gets loaded, but then the current environment gets switched, and CSV.jl is loaded and the right versions can’t be resolved quite right and it’s assumed that the already loaded Parsers module is the “right one”.

This can usually be fixed by pinning Parsers.jl to v1.2.1 for the time being. A new CSV.jl release compatible with Parsers.jl 2.0 is coming soon, hopefully in the next week or so.

---

<div class="post-metadata">

**Author:** ![erickn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/erickn/32/27431_2.png) [@erickn](https://discourse.julialang.org/u/erickn)\
**Post date:** [August 30, 2021, 1:33am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/4 "2021-08-30T01:33:54Z")

</div>

Thank for the explanation. I kinda suspected what you mentioned from the line where the issue occurs and by looking through the master branch. But, I did not know IJulia can behave that way, so I ended up putting up this question. Good to know.

---

<div class="post-metadata">

**Author:** ![compleat](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/compleat/32/8958_2.png) [@compleat](https://discourse.julialang.org/u/compleat)\
**Post date:** [September 1, 2021, 11:47am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/5 "2021-09-01T11:47:37Z")

</div>

Hiya, I am not exactly a ‘newbie’ but I have not used pinning before… I wonder if you might be able to give me a hint as to how I would achieve the ‘pinning’? [and thanks for your help here]

I tried

```julia
] add Parsers@1.2.1

```

But got pages of ‘Unsatisfiable requirements’  
Thanks for any help getting back ‘on the road’ again.

Error message:

```julia
Unsatisfiable requirements detected for package Parsers [69de0a69]:
 Parsers [69de0a69] log:
 \u251c\u2500possible versions are: 0.1.0-2.0.3 or uninstalled
 \u2514\u2500restricted to versions 1.2.1 by an explicit requirement \u2014 no versions left

Stacktrace:
  [1] check_constraints(graph::Pkg.Resolve.Graph)
    @ Pkg.Resolve /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Resolve/graphtype.jl:978
  [2] Pkg.Resolve.Graph(versions::Dict{Base.UUID, Set{VersionNumber}}, deps::Dict{Base.UUID, Dict{VersionNumber, Dict{String, Base.UUID}}}, compat::Dict{Base.UUID, Dict{VersionNumber, Dict{String, Pkg.Types.VersionSpec}}}, uuid_to_name::Dict{Base.UUID, String}, reqs::Dict{Base.UUID, Pkg.Types.VersionSpec}, fixed::Dict{Base.UUID, Pkg.Resolve.Fixed}, verbose::Bool, julia_version::VersionNumber)
    @ Pkg.Resolve /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Resolve/graphtype.jl:371
  [3] deps_graph(ctx::Pkg.Types.Context, uuid_to_name::Dict{Base.UUID, String}, reqs::Dict{Base.UUID, Pkg.Types.VersionSpec}, fixed::Dict{Base.UUID, Pkg.Resolve.Fixed})
    @ Pkg.Operations /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Operations.jl:537
  [4] resolve_versions!(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec})
    @ Pkg.Operations /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Operations.jl:407
  [5] targeted_resolve(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}, preserve::Pkg.Types.PreserveLevel)
    @ Pkg.Operations /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Operations.jl:1214
  [6] tiered_resolve(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec})
    @ Pkg.Operations /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Operations.jl:1200
  [7] _resolve
    @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Operations.jl:1220 [inlined]
  [8] add(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}, new_git::Vector{Base.UUID}; preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform)
    @ Pkg.Operations /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/Operations.jl:1235
  [9] add(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}; preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform, kwargs::Base.Iterators.Pairs{Symbol, IJulia.IJuliaStdio{Base.PipeEndpoint}, Tuple{Symbol}, NamedTuple{(:io,), Tuple{IJulia.IJuliaStdio{Base.PipeEndpoint}}}})
    @ Pkg.API /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/API.jl:204
 [10] add(pkgs::Vector{Pkg.Types.PackageSpec}; io::IJulia.IJuliaStdio{Base.PipeEndpoint}, kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ Pkg.API /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/API.jl:80
 [11] add(pkgs::Vector{Pkg.Types.PackageSpec})
    @ Pkg.API /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/API.jl:78
 [12] do_cmd!(command::Pkg.REPLMode.Command, repl::IJulia.MiniREPL)
    @ Pkg.REPLMode /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/REPLMode/REPLMode.jl:408
 [13] do_cmd(repl::IJulia.MiniREPL, input::String; do_rethrow::Bool)
    @ Pkg.REPLMode /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/REPLMode/REPLMode.jl:386
 [14] top-level scope
    @ In[24]:1
 [15] eval
    @ ./boot.jl:360 [inlined]
 [16] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
    @ Base ./loading.jl:1116

```

Thanks

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<div class="post-metadata">

**Author:** ![jling](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jling/32/212909_2.png) [@jling](https://discourse.julialang.org/u/jling)\
**Post date:** [September 1, 2021, 12:05pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/6 "2021-09-01T12:05:02Z")

</div>

> [@compleat](#):
>
> Unsatisfiable requirements

please paste the full error message other wise it’s impossible for people to debug for you

---

<div class="post-metadata">

**Author:** ![compleat](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/compleat/32/8958_2.png) [@compleat](https://discourse.julialang.org/u/compleat)\
**Post date:** [September 1, 2021, 12:08pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/7 "2021-09-01T12:08:26Z")

</div>

Thanks - see above

Could I roll back versions of CSV? What would be the one?

---

<div class="post-metadata">

**Author:** ![erickn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/erickn/32/27431_2.png) [@erickn](https://discourse.julialang.org/u/erickn)\
**Post date:** [September 2, 2021, 6:31am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/8 "2021-09-02T06:31:39Z")

</div>

It turns out that pinning the version does not work in the notebook for me. Still looking for an answer for this…

---

<div class="post-metadata">

**Author:** ![lmiq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lmiq/32/18314_2.png) [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Post date:** [September 2, 2021, 6:47am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/9 "2021-09-02T06:47:26Z")

</div>

Check this: [Issues with CSV in Julia 1.6.2 - #23 by lmiq](https://discourse.julialang.org/t/issues-with-csv-in-julia-1-6-2/67507/23)

And that thread in general for some other ideas.

---

<div class="post-metadata">

**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [September 2, 2021, 6:59am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/10 "2021-09-02T06:59:07Z")

</div>

> [@erickn](#):
>
> It turns out that pinning the version does not work in the notebook for me. Still looking for an answer for this…

Loading `IJulia` for work with Jupyter will load `Parsers@v2`. Activating your notebook then activates an environment requiring `Parsers@v1.1.2`, which will fail since `Parsers@v2` is already loaded. The solution should be to pin `Parsers` in the environment where `IJulia` is loaded (_before_ loading `IJulia`), which may be different than your notebook environment.

If you use the notebook viewer in VSCode instead of Jupyter directly, you shouldn’t have the problem at all, since VSCode seperates code required for viewing & modifying a notebook properly from the code running inside of that notebook.

---

<div class="post-metadata">

**Author:** ![erickn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/erickn/32/27431_2.png) [@erickn](https://discourse.julialang.org/u/erickn)\
**Post date:** [September 2, 2021, 5:45pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/11 "2021-09-02T17:45:32Z")

</div>

@Sukera It is a super helpful hint! Unfortunately, Julia notebooks in VSCode did not work for me, either.

I tracked down what’s happening again with your hint, and I found that `Conda.jl` depends on `JSON.jl`, `JSON.jl` on `Parsers.jl` in turn. The `Parsers.jl` `compat` option in `JSON.jl` is `1, 2`, which leads to loading `Parsers.jl` v2 by Jupyter.

So when the `compat` option is modified to `1`, `CSV.jl` now gets loaded in Jupyter.

I have not tested the functionality of `CSV.jl` fully yet. I looked through what `JSON.jl` uses from `Parsers.jl`, and I do not think this monkey patch would affect things negatively.

---

<div class="post-metadata">

**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [September 2, 2021, 6:21pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/12 "2021-09-02T18:21:07Z")

</div>

> [@erickn](#):
>
> I looked through what `JSON.jl` uses from `Parsers.jl` , and I do not think this monkey patch would affect things negatively.

I wouldn’t expect it to - it’s the two different versions that muck things up, not whatever JSON.jl patches in.

* * *

Since it happens with Conda.jl as well, I suspect this is a good bit worse - anything that happens to load `Parsers@v2` (even rightfully so) where subsequently something else is bound to load `Parsers@v1` will run into this, because there can only be one version of a package loaded at a time. In theory, downgrading the `Parsers` version by loading e.g. `CSV.jl@v0.8.5` _should_ cause `Conda.jl` to also reload, since either `Conda.jl` can’t rely on 2.0 functionality that it’s now been compiled with, or `CSV.jl` breaks because it isn’t compatible with `Parsers@v2`.

The “general” solution should be to load packages in such an order that the versions of their dependencies grow maximally while obeying all versions bounds. This is not that easy to do manually sadly. Thankfully, there are only [6 direct dependents of `Parsers`](https://juliahub.com/ui/Packages/Parsers/833b9/2.0.3?t=2). The vast majority of its 1848 dependencies are through `JSON.jl` , which has 1787 dependencies (so “only” 61 dependencies of `Parsers` that are not using `JSON` could be hit by this).

I have no idea how many users access each of those dependencies - I suspect most that are hit by this are using either IJulia in a Jupyter notebook, Conda or CSV directly. I’ll crosspost this finding about Conda to the issue, thanks for investigating.

---

<div class="post-metadata">

**Author:** ![erickn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/erickn/32/27431_2.png) [@erickn](https://discourse.julialang.org/u/erickn)\
**Post date:** [September 2, 2021, 9:53pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/13 "2021-09-02T21:53:43Z")

</div>

@Sukera I agree with what you commented. The right way to deal with this is at the level of packages, e.g. how packages are loaded correctly and properly. I do not recommend the monkey patch that I did in any way. It is at your own risk, no warranty. 😉

And thank you for cross-posting. Keep me posted.

---

<div class="post-metadata">

**Author:** ![hammer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hammer/32/5807_2.png) [@hammer](https://discourse.julialang.org/u/hammer)\
**Post date:** [September 15, 2021, 6:36pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/14 "2021-09-15T18:36:08Z")

</div>

> [@Sukera](#):
>
> If you use the notebook viewer in VSCode instead of Jupyter directly, you shouldn’t have the problem at all, since VSCode seperates code required for viewing & modifying a notebook properly from the code running inside of that notebook.

I don’t mean to derail this thread but I’m curious to learn more about isolation of the notebook environment from content in Jupyter and VS Code. I tried searching a few phrases but could not turn up relevant links. @Sukera do you happen to have links to where I might learn more about how Jupyter and VS Code differ in this regard?

---

<div class="post-metadata">

**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [September 15, 2021, 7:34pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/15 "2021-09-15T19:34:39Z")

</div>

> [@hammer](#):
>
> @Sukera do you happen to have links to where I might learn more about how Jupyter and VS Code differ in this regard?

I don’t have a link with a writeup of differences at hand and I don’t think such a summary exists yet. What I can tell you from my understanding though is that, as far as I know, it boils down to Jupyter using the stacking behavior of environments as the code in question is using for running. This leads to the observed clash. In contrast, VSCode has a seperate environment and julia instance, combined with a seperate parser, to isolate the linting/code checking environment from the environment of the code that you’re writing.

This may not be 100% accurate, but I think that’s the distinction this boils down to. If the code that’s doing the linting doesn’t influence the code that’s running, it’s a better situation.

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<div class="post-metadata">

**Author:** ![davidanthoff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/davidanthoff/32/223493_2.png) [@davidanthoff](https://discourse.julialang.org/u/davidanthoff)\
**Post date:** [September 15, 2021, 8:58pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/16 "2021-09-15T20:58:34Z")

</div>

The strategy in VS Code is that we never load the code from the packages we use via the normal package loading mechanism, but instead we have one global module called `VSCodeServer`, and then we essentially `include` all the code from packages that we want to use into that global module. That way none of these packages appear to be “loaded” already from Julia’s point of view, and then a user can load a different version of the same package via the normal `using` or `import` mechanism.

If you want to see the details, here is some more info:

- The top level file that we load into the notebook kernel process is [this](https://github.com/julia-vscode/julia-vscode/blob/b8d2cf28cd7715ae02b7107f318a10cf41e2179f/scripts/notebook/notebook.jl). Note how we manipulate `LOAD_PATH` temporarily there to make sure we will load the package `VSCodeServer` from a specific location on disc.
- Inside `VSCodeServer` we then load lots of other packages that we use, that code starts [here](https://github.com/julia-vscode/julia-vscode/blob/b8d2cf28cd7715ae02b7107f318a10cf41e2179f/scripts/packages/VSCodeServer/src/VSCodeServer.jl#L24). But note how we _never_ say e.g. `using JSON`, instead we `include` the root file for JSON.jl. That way JSON.jl is loaded as just a child module of `VSCodeServer`. If a user later at the REPL writes `using JSON`, the Julia module loading system will just load whatever version of JSON the user has in their environment, and that can be a different version of `JSON` from the one we loaded inside `VSCodeServer`.
- This method of including packages gets tricky if you have a package that itself relies on some other package. We get around that by working with those packages and begging them to structure their source code slightly differently, with a `packagedef.jl` file, so that we can load those packages in such a way that they will actually use say the version of JSON.jl that we previously loaded into `VSCodeServer`, instead of trying to load a “global” version of JSON.jl. So this is not a generic approach, but it works well enough as long as all the packages we want to use make this small structural change that doesn’t really have any impact on normal operations.

The short version of all of this is that VS Code loads a lot of packages into the notebook kernel process, but all of those are “hidden” inside `VSCodeServer` and thus a user can load a different version of those packages in their code without problems.

---

<div class="post-metadata">

**Author:** ![compleat](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/compleat/32/8958_2.png) [@compleat](https://discourse.julialang.org/u/compleat)\
**Post date:** [November 9, 2021, 8:36pm UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/17 "2021-11-09T20:36:25Z")

</div>

I thought this issue was meant to be resolved by recent releases, but apparently not. Many of my students cannot add CSV still! They are using Julia 1.6.3 and the latest version of the packages, including IJulia. Is there any simple fix and/or any hope for this problem being resolved in future package versions?  
[A nightmare for me!]

I remember that after several hours of fiddling around (possibly using suggestions above), I got everything working, but that was 2 months ago and I forgot what worked(!)

I am suggesting to my students that (inside the Julia REPL) they remove Parsers, then add CSV, and then build IJulia, and then they should restart Jupyter.

I could not try this myself (because I don’t want to fix what isn’t broken on my machine), but would appreciate suggestions on this course of action.

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**Author:** ![oizin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oizin/32/6220_2.png) [@oizin](https://discourse.julialang.org/u/oizin)\
**Post date:** [December 8, 2021, 2:20am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/18 "2021-12-08T02:20:51Z")

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Has there been any resolution to the problem or suggested workaround? I tried using CSVFiles but got the same error

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**Author:** ![jling](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jling/32/212909_2.png) [@jling](https://discourse.julialang.org/u/jling)\
**Post date:** [December 8, 2021, 2:29am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/19 "2021-12-08T02:29:41Z")

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this should be resolved, what version are you using?

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**Author:** ![oizin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oizin/32/6220_2.png) [@oizin](https://discourse.julialang.org/u/oizin)\
**Post date:** [December 8, 2021, 4:48am UTC](https://discourse.julialang.org/t/csv-jl-fails-precompling-typeerror-in-type-expression-expected-unionall-got-type-parsers-options/67195/20 "2021-12-08T04:48:04Z")

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😅 Yes it is thanks! I was sure I’d updated but obviously hadn’t.