# Ghost function surviving between package versions

**URL:** <https://discourse.julialang.org/t/ghost-function-surviving-between-package-versions/52812>\
**Category:** General Usage\
**Tags:** package\
**Created:** [January 4, 2021, 9:08am UTC](https://discourse.julialang.org/t/ghost-function-surviving-between-package-versions/52812 "2021-01-04T09:08:45Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![virgile-baudrot](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/virgile-baudrot/32/6857_2.png) [@virgile-baudrot](https://discourse.julialang.org/u/virgile-baudrot)\
**Post date:** [January 4, 2021, 9:08am UTC](https://discourse.julialang.org/t/ghost-function-surviving-between-package-versions/52812/1 "2021-01-04T09:08:45Z")

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Dear all,

I made a package with a function called `runMCMC` returning a `DataFrame` in version 0.2.0 and an `Array` in version 0.3.0 (ok, I should have upgrade to 1.0.0 but it’s quite confidential for now).

I send 0.2.0 to a friend and then 0.3.0 and after moving from folder, doing `activate .` in that new folder and `instantiate`, checking `status` gives 0.3.0 and while some other new functions run properly, that specific function `runMCMC` whose behavior changed between 0.2.0 and 0.3.0, it still returns a `DataFrame`…

Of course, on my computer, it return an `Array` as expected for version 0.3.0. So it’s like every thing upgrade properly on my friend’s computer except `runMCMC` acting like a ghost…

What can I ask her to solve it?

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**Author:** ![pfitzseb](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pfitzseb/32/45566_2.png) [@pfitzseb](https://discourse.julialang.org/u/pfitzseb)\
**Post date:** [January 4, 2021, 9:12am UTC](https://discourse.julialang.org/t/ghost-function-surviving-between-package-versions/52812/2 "2021-01-04T09:12:24Z")

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If the workflow was

1. Start Julia and load 0.2.0
2. Copy over new package version and `activate .` that dir
3. Load package again

without restarting Julia, then that’s expected behaviour – you can’t load a different version of a package if it’s already loaded.

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**Author:** ![virgile-baudrot](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/virgile-baudrot/32/6857_2.png) [@virgile-baudrot](https://discourse.julialang.org/u/virgile-baudrot)\
**Post date:** [January 4, 2021, 9:46am UTC](https://discourse.julialang.org/t/ghost-function-surviving-between-package-versions/52812/3 "2021-01-04T09:46:32Z")

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Thank you. We’ll try this. But we actually restarted Julia.