# Strange Pkg warning in 1.7

**URL:** <https://discourse.julialang.org/t/strange-pkg-warning-in-1-7/72412>\
**Category:** Package Management\
**Tags:** pkg\
**Created:** [December 1, 2021, 10:34pm UTC](https://discourse.julialang.org/t/strange-pkg-warning-in-1-7/72412 "2021-12-01T22:34:26Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![amrods](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/amrods/32/2543_2.png) [@amrods](https://discourse.julialang.org/u/amrods)\
**Post date:** [December 1, 2021, 10:34pm UTC](https://discourse.julialang.org/t/strange-pkg-warning-in-1-7/72412/1 "2021-12-01T22:34:26Z")

</div>

I installed Julia 1.7, and now I am getting a warning when loading some packages (I opened an issue [here](https://github.com/SciML/PreallocationTools.jl/issues/12) in the package repo). In particular, using PreallocationTools after loading ForwardDiff in Julia 1.7 results in this warning:

```julia
julia> using ForwardDiff

julia> using PreallocationTools
┌ Warning: Replacing module `ForwardDiff`
└ @ Base loading.jl:1036

```

Furthermore, if I try to use Optim after the previous 2 commands I get:

```julia
julia> using Optim
[Info: Precompiling Optim [429524aa-4258-5aef-a3af-852621145aeb]
┌ Warning: Module ForwardDiff with build ID 2902110846083 is missing from the cache.
│ This may mean ForwardDiff [f6369f11-7733-5829-9624-2563aa707210] does not support precompilation but is imported by a module that does.
└ @ Base loading.jl:1107
┌ Warning: Module ForwardDiff with build ID 2902110846083 is missing from the cache.
│ This may mean ForwardDiff [f6369f11-7733-5829-9624-2563aa707210] does not support precompilation but is imported by a module that does.
└ @ Base loading.jl:1107
[Info: Skipping precompilation since __precompile__ (false). Importing Optim [429524aa-4258-5aef-a3af-852621145aeb].
[Info: Precompiling NLSolversBase [d41bc354-129a-5804-8e4c-c37616107c6c]
┌ Warning: Module ForwardDiff with build ID 2902110846083 is missing from the cache.
│ This may mean ForwardDiff [f6369f11-7733-5829-9624-2563aa707210] does not support precompilation but is imported by a module that does.
└ @ Base loading.jl:1107
[Info: Skipping precompilation since __precompile__ (false). Importing NLSolversBase [d41bc354-129a-5804-8e4c-c37616107c6c].
[Info: Precompiling LineSearches [d3d80556-e9d4-5f37-9878-2ab0fcc64255]
┌ Warning: Module NLSolversBase with build ID 3475646636699 is missing from the cache.
│ This may mean NLSolversBase [d41bc354-129a-5804-8e4c-c37616107c6c] does not support precompilation but is imported by a module that does.
└ @ Base loading.jl:1107
[Info: Skipping precompilation since __precompile__ (false). Importing LineSearches [d3d80556-e9d4-5f37-9878-2ab0fcc64255].

```

How can I fix this?