# Do I need to re-dowload packages when I downgrade Julia?

**URL:** <https://discourse.julialang.org/t/do-i-need-to-re-dowload-packages-when-i-downgrade-julia/100356>\
**Category:** Package Management\
**Tags:** package, package-manager, versions, juliaup\
**Created:** [June 14, 2023, 7:00pm UTC](https://discourse.julialang.org/t/do-i-need-to-re-dowload-packages-when-i-downgrade-julia/100356 "2023-06-14T19:00:45Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![bertulli](https://avatars.discourse-cdn.com/v4/letter/b/ecc23a/32.png) [@bertulli](https://discourse.julialang.org/u/bertulli)\
**Post date:** [June 14, 2023, 7:00pm UTC](https://discourse.julialang.org/t/do-i-need-to-re-dowload-packages-when-i-downgrade-julia/100356/1 "2023-06-14T19:00:45Z")

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Hi all!

I am having some troubles using `PackageCompiler` recently (whereas it worked fine with Julia 1.8 ~6 months ago), so I thought I needed to downgrade my Julia installation. I tried `juliaup` and worked fine, installing v1.8.5.

My question is: are there any steps I should do to keep external packages in a compatible state between the two versions? I know files in `~/.julia/environments/` serve this purpose, but may this cause problems with the precompilation of packages? I don’t know, do I need to delete `~/.julia/artifacts` or `~/.julia/compiled` or anything else when switching? Maybe running `] instantiate`?

Thanks!

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**Author:** ![Oscar\_Smith](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oscar_smith/32/25343_2.png) [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)\
**Post date:** [June 14, 2023, 7:35pm UTC](https://discourse.julialang.org/t/do-i-need-to-re-dowload-packages-when-i-downgrade-julia/100356/2 "2023-06-14T19:35:18Z")

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just re-instantiating should work.

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<div class="post-metadata">

**Author:** ![bertulli](https://avatars.discourse-cdn.com/v4/letter/b/ecc23a/32.png) [@bertulli](https://discourse.julialang.org/u/bertulli)\
**Post date:** [June 14, 2023, 10:29pm UTC](https://discourse.julialang.org/t/do-i-need-to-re-dowload-packages-when-i-downgrade-julia/100356/3 "2023-06-14T22:29:35Z")

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Thanks! But if I try to do `] instantiate` in the (already instantiated) project, I get

```julia
(ARMCortexM4Model) pkg> instantiate
┌ Warning: The active manifest file has dependencies that were resolved with a different julia version (1.9.0). Unexpected behavior may occur.

```

(where `ARMCortexM4Model` is my project). Deleting `Manifest.toml` solves it. Is this all that is needed?

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<div class="post-metadata">

**Author:** ![Oscar\_Smith](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oscar_smith/32/25343_2.png) [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)\
**Post date:** [June 14, 2023, 10:35pm UTC](https://discourse.julialang.org/t/do-i-need-to-re-dowload-packages-when-i-downgrade-julia/100356/4 "2023-06-14T22:35:43Z")

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oh right, you may need to `resolve` also.