Nervesで「nerves_system_*」の都合により「Major version mismatch between host and target Erlang/OTP versions」が発生する場合の対処方法

** (Mix) Major version mismatch between host and target Erlang/OTP versions
  Host version: 22
  Target version: 23

  # Run "mix help deps" to learn about dependencies.
  defp deps do
    [
      # Dependencies for all targets
      {:nerves, "~> 1.6.0", runtime: false},

〜中略〜

      # Dependencies for specific targets
      {:nerves_system_rpi, "~> 1.12", runtime: false, targets: :rpi},
      {:nerves_system_rpi0, "~> 1.12", runtime: false, targets: :rpi0},
      {:nerves_system_rpi2, "~> 1.12", runtime: false, targets: :rpi2},
      {:nerves_system_rpi3, "~> 1.12", runtime: false, targets: :rpi3},
      {:nerves_system_rpi3a, "~> 1.12", runtime: false, targets: :rpi3a},
      {:nerves_system_rpi4, "~> 1.12", runtime: false, targets: :rpi4},
      {:nerves_system_bbb, "~> 2.7", runtime: false, targets: :bbb},
      {:nerves_system_x86_64, "~> 1.12", runtime: false, targets: :x86_64},
    ]
  end

** (Mix) Major version mismatch between host and target Erlang/OTP versions
  Host version: 22
  Target version: 23

This will likely cause Erlang code compiled for the target to fail in
unexpected ways.

The easiest way to resolve this issue is to install the same version of
Erlang/OTP on your host. See the Nerves installation guide for doing this
using the `asdf` version manager.

The Nerves System (nerves_system_*) dependency determines the OTP version
running on the target. It is possible that a recent update to the Nerves
System pulled in a new version of Erlang/OTP. If you are using an official
Nerves System, you can verify this by reviewing the CHANGELOG.md file that
comes with the release. Run 'mix deps' to see the Nerves System version and
go to that system's repository on https://github.com/nerves-project.

If you need to run a particular version of Erlang/OTP on your target, you can
either lock the nerves_system_* dependency in your mix.exs to an older
version. Note that this route prevents you from receiving security updates
from the official systems. The other option is to build a custom Nerves
system. See the Nerves documentation for building a custom system and then
run 'make menuconfig' and look for the Erlang options.

$asdf install erlang 23.0.3
$asdf local erlang 23.0.3
$asdf install elixir 1.10.4-otp-23
$asdf local elixir 1.10.4-otp-23

  # Run "mix help deps" to learn about dependencies.
  defp deps do
    [
      # Dependencies for all targets
      {:nerves, "~> 1.6.0", runtime: false},

〜中略〜

      # Dependencies for specific targets
      {:nerves_system_rpi, "~> 1.11.1", runtime: false, targets: :rpi},
      {:nerves_system_rpi0, "~> 1.11.1", runtime: false, targets: :rpi0},
      {:nerves_system_rpi2, "~> 1.11.1", runtime: false, targets: :rpi2},
      {:nerves_system_rpi3, "~> 1.11.1", runtime: false, targets: :rpi3},
      {:nerves_system_rpi3a, "~> 1.11.1", runtime: false, targets: :rpi3a},
      {:nerves_system_rpi4, "~> 1.11.1", runtime: false, targets: :rpi4},
      {:nerves_system_bbb, "~> 2.6", runtime: false, targets: :bbb},
      {:nerves_system_x86_64, "~> 1.11.1", runtime: false, targets: :x86_64},
    ]
  end

** (Mix) Hex dependency resolution failed, change the version requirements of your dependencies or unlock them (by using mix deps.update or mix deps.unlock). If you are unable to resolve the conflicts you can try overriding with {:dependency, "~> 1.0", override: true}

$ mix deps.update
** (Mix) "mix deps.update" expects dependencies as arguments or the --all option to update all dependencies

$ mix deps.update --all

Resolving Hex dependencies...
Dependency resolution completed:

〜（中略）〜

Downgraded:
  nerves_system_bbb 2.7.1 => 2.6.1
  nerves_system_br 1.12.0 => 1.11.2
  nerves_system_rpi 1.12.1 => 1.11.1
  nerves_system_rpi0 1.12.1 => 1.11.1
  nerves_system_rpi2 1.12.1 => 1.11.1
  nerves_system_rpi3 1.12.1 => 1.11.1
  nerves_system_rpi3a 1.12.1 => 1.11.1
  nerves_system_rpi4 1.12.1 => 1.11.2
  nerves_system_x86_64 1.12.1 => 1.11.1
New:
  nerves_system_linter 0.3.0
* Updating nerves_system_rpi (Hex package)
* Updating nerves_system_rpi0 (Hex package)
* Updating nerves_system_rpi2 (Hex package)
* Updating nerves_system_rpi3 (Hex package)
* Updating nerves_system_rpi3a (Hex package)
* Updating nerves_system_rpi4 (Hex package)
* Updating nerves_system_bbb (Hex package)
* Updating nerves_system_x86_64 (Hex package)
* Updating nerves_system_br (Hex package)
* Getting nerves_system_linter (Hex package)

Nerves environment
  MIX_TARGET:   rpi0
  MIX_ENV:      dev

Resolving Nerves artifacts...
  Resolving nerves_system_rpi0
  => Trying https://github.com/nerves-project/nerves_system_rpi0/releases/download/v1.11.1/nerves_system_rpi0-portable-1.11.1-38F032F.tar.gz
|==================================================| 100% (141 / 141) MB
  => Success
  Cached nerves_toolchain_armv6_rpi_linux_gnueabi
$