# Package names could not be resolved: \* MyPkg (91bcb2...e67b in manifest but not in project)

**URL:** <https://discourse.julialang.org/t/package-names-could-not-be-resolved-mypkg-91bcb2-e67b-in-manifest-but-not-in-project/45679>\
**Category:** General Usage\
**Tags:** question, package, error\
**Created:** [August 28, 2020, 11:13am UTC](https://discourse.julialang.org/t/package-names-could-not-be-resolved-mypkg-91bcb2-e67b-in-manifest-but-not-in-project/45679 "2020-08-28T11:13:04Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Luapulu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/luapulu/32/17669_2.png) [@Luapulu](https://discourse.julialang.org/u/Luapulu)\
**Post date:** [August 28, 2020, 11:13am UTC](https://discourse.julialang.org/t/package-names-could-not-be-resolved-mypkg-91bcb2-e67b-in-manifest-but-not-in-project/45679/1 "2020-08-28T11:13:04Z")

</div>

**Minimal Example**  
I’m running julia1.3. I have a minimal Package called MyPkg. It contains a Project.toml file and a src folder with a MyPkg.jl file that is empty.

```julia
.
|-- Project.toml
`-- src
    `-- MyPkg.jl

```

The Project.toml looks like this:

```julia
name = "MyPkg"
uuid = "91bcb29e-4cb6-43fb-982d-23ba0ee3e67b"
authors = ["Author"]
version = "0.1.0"

```

I want to use this package for the project I’m working on. So, I have a folder for my project with the following structure:

```julia
.
|-- Manifest.toml
|-- Project.toml
|-- README.md
`-- runs
    `-- full-spectrum
        `-- main.jl

```

Now, I want to add MyPkg to the environment for my project. So, I have:

```julia
(MyProject) pkg> add path/to/MyPkg

```

Note that I get the same error if I try adding the package by using the url to the git repo.

This gives me the following Project.toml:

```julia
name = "MyProject"
uuid = "3e7b5bd9-e9fd-4c85-9fed-c9a4b702d0db"
authors = ["Author"]
version = "0.1.0"

[deps]
MyPkg = "91bcb29e-4cb6-43fb-982d-23ba0ee3e67b"

```

and Mainfest.toml:

```julia
# This file is machine-generated - editing it directly is not advised

[[MyPkg]]
git-tree-sha1 = "3282257cf25a6115791bbebede1bf60bf968e396"
repo-rev = "master"
repo-url = "../MyPkg"
uuid = "91bcb29e-4cb6-43fb-982d-23ba0ee3e67b"
version = "0.1.0"

```

Finally, I try to dev the package:

```julia
(MyProject) pkg> dev MyPkg
  Updating registry at `~/.julia/registries/General`
  Updating git-repo `https://github.com/JuliaRegistries/General.git`
ERROR: The following package names could not be resolved:
 * MyPkg (91bcb29e-4cb6-43fb-982d-23ba0ee3e67b in manifest but not in project)
Please specify by known `name=uuid`.

```

**Question**  
How does that error make sense? I want to be able to make changes to MyPkg without commiting to a git repo and use those changes in MyProject. I thought dev was the way to do that.

---

<div class="post-metadata">

**Author:** ![Henrique\_Becker](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/henrique_becker/32/15443_2.png) [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Post date:** [August 28, 2020, 1:48pm UTC](https://discourse.julialang.org/t/package-names-could-not-be-resolved-mypkg-91bcb2-e67b-in-manifest-but-not-in-project/45679/2 "2020-08-28T13:48:31Z")

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Hmmm, I can be wrong there, but you often do not `add` and `dev` the same package, you just do one of them. If you want to have your package as a dependency inside your project, and keep editing the package, `activate` the environment for your project and `dev` your package there (using the path, as you did with `add`), but do not `add` it.

---

<div class="post-metadata">

**Author:** ![Luapulu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/luapulu/32/17669_2.png) [@Luapulu](https://discourse.julialang.org/u/Luapulu)\
**Post date:** [August 28, 2020, 2:04pm UTC](https://discourse.julialang.org/t/package-names-could-not-be-resolved-mypkg-91bcb2-e67b-in-manifest-but-not-in-project/45679/3 "2020-08-28T14:04:05Z")

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Ahhh, yes you’re absolutely right. Thank you!