# Package update race

**URL:** <https://discourse.julialang.org/t/package-update-race/40584>\
**Category:** General Usage\
**Tags:** pkg, versions\
**Created:** [June 1, 2020, 9:55pm UTC](https://discourse.julialang.org/t/package-update-race/40584 "2020-06-01T21:55:52Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![heliosdrm](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/heliosdrm/32/3851_2.png) [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Post date:** [June 1, 2020, 9:55pm UTC](https://discourse.julialang.org/t/package-update-race/40584/1 "2020-06-01T21:55:52Z")

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Time ago I asked something similar to this, but not exactly the same; and I still have some doubts about what is expected to happen when an environment has added two packages with a common dependency, in a situation like this:

Package `A` has two versions:

- `A@1.0.0` with no dependency.
- `A@2.0.0` depending on `D` with compat `D = "1"`.

Package `B` has also two versions:

- `B@1.0.0` depending on `D` with compat `D = "1"`.
- `B@2.0.0` with updated compat `D = "2"`

This allows the following combinations of `A` and `B`:

1. `A@1.0.0` and `B@1.0.0` (with `D = "1"`)
2. `A@2.0.0` and `B@1.0.0` (with `D = "1"`)
3. `A@1.0.0` and `B@2.0.0` (with `D = "2"`)

Let’s suppose that in Day 1, `A` is updated to v2.0.0; and in Day 2 `D` and `B` update their versions. I’d expect that if I had updated my environment in Day 1 - i.e. I was in status #2, I will remain there. I mean, if after Day 2 I try to update again, nothing will happen… or would `A` be downgraded and I would move to status #3?

And what will happen if I do nothing in Day 1, and I try to update (or just add) `A` and `B` after Day 2? Will I be in status #2 or #3? Or that’s not well defined and depends on particular conditions, e.g. which package is attempted to be updated first?