Fail to install on MacOS

[harryprince]

julia> import Pkg; Pkg.add("COPT")
   Resolving package versions...
ERROR: Unsatisfiable requirements detected for package MathOptInterface [b8f27783]:
 MathOptInterface [b8f27783] log:
 ├─possible versions are: 0.5.0-1.6.1 or uninstalled
 ├─restricted by compatibility requirements with COPT [227a2e2d] to versions: 1.0.0-1.6.1
 │ └─COPT [227a2e2d] log:
 │   ├─possible versions are: 1.0.0-1.0.4 or uninstalled
 │   └─restricted to versions * by an explicit requirement, leaving only versions 1.0.0-1.0.4
 └─restricted by compatibility requirements with GAMS [1ca51c6a] to versions: [0.9.13-0.9.22, 0.10.7-0.10.9] — no versions left
   └─GAMS [1ca51c6a] log:
     ├─possible versions are: 0.1.0-0.3.4 or uninstalled
     └─restricted to versions * by an explicit requirement, leaving only versions 0.1.0-0.3.4
Stacktrace:
  [1] propagate_constraints!(graph::Pkg.Resolve.Graph, sources::Set{Int64}; log_events::Bool)
    @ Pkg.Resolve /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Resolve/graphtype.jl:1063
  [2] propagate_constraints! (repeats 2 times)
    @ /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Resolve/graphtype.jl:1000 [inlined]
  [3] simplify_graph!(graph::Pkg.Resolve.Graph, sources::Set{Int64}; clean_graph::Bool)
    @ Pkg.Resolve /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Resolve/graphtype.jl:1519
  [4] simplify_graph! (repeats 2 times)
    @ /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Resolve/graphtype.jl:1519 [inlined]
  [5] resolve_versions!(env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, julia_version::VersionNumber)
    @ Pkg.Operations /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Operations.jl:335
  [6] targeted_resolve(env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, preserve::Pkg.Types.PreserveLevel, julia_version::VersionNumber)
    @ Pkg.Operations /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Operations.jl:1154
  [7] tiered_resolve(env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, julia_version::VersionNumber)
    @ Pkg.Operations /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Operations.jl:1139
  [8] _resolve(io::Base.TTY, env::Pkg.Types.EnvCache, registries::Vector{Pkg.Registry.RegistryInstance}, pkgs::Vector{Pkg.Types.PackageSpec}, preserve::Pkg.Types.PreserveLevel, julia_version::VersionNumber)
    @ Pkg.Operations /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Operations.jl:1160
  [9] add(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}, new_git::Set{Base.UUID}; preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform)
    @ Pkg.Operations /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/Operations.jl:1176
 [10] add(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}; preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform, kwargs::Base.Pairs{Symbol, Base.TTY, Tuple{Symbol}, NamedTuple{(:io,), Tuple{Base.TTY}}})
    @ Pkg.API /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/API.jl:268
 [11] add(pkgs::Vector{Pkg.Types.PackageSpec}; io::Base.TTY, kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ Pkg.API /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/API.jl:149
 [12] add(pkgs::Vector{Pkg.Types.PackageSpec})
    @ Pkg.API /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/API.jl:144
 [13] #add#27
    @ /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/API.jl:142 [inlined]
 [14] add
    @ /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/API.jl:142 [inlined]
 [15] #add#26
    @ /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/API.jl:141 [inlined]
 [16] add(pkg::String)
    @ Pkg.API /usr/local/Cellar/julia/1.7.0_1/share/julia/stdlib/v1.7/Pkg/src/API.jl:141
 [17] top-level scope
    @ REPL[14]:1

[lschork2]

The installation fails because you have already GAMS installed and GAMS and COPT depend on incompatible versions of MathOptInterface. When you do not need to use GAMS and COPT at the same time, you can install COPT in a different Julia environment:

julia> mkdir("Project1")
julia> cd("Project1")
julia> # press `]` to activate the package REPL mode...
(v1.7) pkg> activate .
(Project1) pkg> add COPT