# ERROR: Unsatisfiable requirements detected for package Cxx \[a0b5b9ef\]:

**URL:** <https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989>\
**Category:** New to Julia\
**Tags:** question, package, cxx\
**Created:** [October 30, 2018, 11:55pm UTC](https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989 "2018-10-30T23:55:52Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![NiklasGustafsson](https://avatars.discourse-cdn.com/v4/letter/n/82dd89/32.png) [@NiklasGustafsson](https://discourse.julialang.org/u/NiklasGustafsson)\
**Post date:** [October 30, 2018, 11:55pm UTC](https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989/1 "2018-10-30T23:55:52Z")

</div>

I’m somewhat new to Julia.

I get this error when trying to add PyCall on Windows 10 with v1.0 of Julia. Is it telling me that PyCall is not supported, or is this some configuration error on my installation?

```julia
C:\...\> julia
               _
   _ _ _(_)_ | Documentation: https://docs.julialang.org
  (_) | (_) (_) |
   _ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` | |
  | | |_| | | | (_| | | Version 1.0.0 (2018-08-08)
 _/ |\ __'_|_|_|\__'_| | Official https://julialang.org/ release
|__/ |

```

julia\> using Pkg

julia\> Pkg.add(“PyCall”)  
Updating registry at `C:\Users\niklasg\.julia\registries\General`  
Updating git-repo `https://github.com/JuliaRegistries/General.git`  
Resolving package versions…  
ERROR: Unsatisfiable requirements detected for package Cxx [a0b5b9ef]:  
Cxx [a0b5b9ef] log:  
├─possible versions are: [0.0.1-0.0.2, 0.1.0-0.1.1, 0.2.0] or uninstalled  
├─restricted to versions \* by an explicit requirement, leaving only versions [0.0.1-0.0.2, 0.1.0-0.1.1, 0.2.0]  
└─restricted by julia compatibility requirements to versions: uninstalled — no versions left  
Stacktrace:  
[1] #propagate\_constraints!#61(::Bool, ::Function, ::Pkg.GraphType.Graph, ::Set{Int64}) at C:\cygwin\home\Administrator\buildbot\worker\package\_win64\build\usr\share\julia\stdlib\v1.0\Pkg\src\GraphType.jl:1005  
[2] propagate\_constraints! at C:\cygwin\home\Administrator\buildbot\worker\package\_win64\build\usr\share\julia\stdlib\v1.0\Pkg\src\GraphType.jl:946 [inlined]  
[3] #simplify\_graph!#121(::Bool, ::Function, ::Pkg.GraphType.Graph, ::Set{Int64}) at C:\cygwin\home\Administrator\buildbot\worker\package\_win64\build\usr\share\julia\stdlib\v1.0\Pkg\src\GraphType.jl:1460  
[4] simplify\_graph! at C:\cygwin\home\Administrator\buildbot\worker\package\_win64\build\usr\share\julia\stdlib\v1.0\Pkg\src\GraphType.jl:1460 [inlined]  
…

```julia

```

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<div class="post-metadata">

**Author:** ![StefanKarpinski](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stefankarpinski/32/24_2.png) [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)\
**Post date:** [October 31, 2018, 12:06am UTC](https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989/2 "2018-10-31T00:06:22Z")

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Cxx doesn’t support 1.0 yet.

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<div class="post-metadata">

**Author:** ![NiklasGustafsson](https://avatars.discourse-cdn.com/v4/letter/n/82dd89/32.png) [@NiklasGustafsson](https://discourse.julialang.org/u/NiklasGustafsson)\
**Post date:** [October 31, 2018, 12:45am UTC](https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989/3 "2018-10-31T00:45:21Z")

</div>

So that means neither does PyCall, then, I take it?

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<div class="post-metadata">

**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [October 31, 2018, 1:30am UTC](https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989/4 "2018-10-31T01:30:49Z")

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PyCall seems to work fine.

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<div class="post-metadata">

**Author:** ![haberdashPI](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/haberdashpi/32/26337_2.png) [@haberdashPI](https://discourse.julialang.org/u/haberdashPI)\
**Post date:** [October 31, 2018, 2:38am UTC](https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989/5 "2018-10-31T02:38:34Z")

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You might be able to successfully add PyCall if you first call `rm Cxx`.

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<div class="post-metadata">

**Author:** ![NiklasGustafsson](https://avatars.discourse-cdn.com/v4/letter/n/82dd89/32.png) [@NiklasGustafsson](https://discourse.julialang.org/u/NiklasGustafsson)\
**Post date:** [October 31, 2018, 5:13pm UTC](https://discourse.julialang.org/t/error-unsatisfiable-requirements-detected-for-package-cxx-a0b5b9ef/16989/6 "2018-10-31T17:13:15Z")

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Yes, that worked. Thanks for the assistance!