From x86 to ARM or Uninstall x86 packages on ARM

[borisboesler]

Output of brew config

HOMEBREW_VERSION: 6.0.18
ORIGIN: https://github.com/Homebrew/brew
HEAD: 5b90e281d4e0c8fbd6ca4d8358276fb305b8d0bd
Last commit: 3 days ago
Branch: stable
Core tap: N/A
Core cask tap: N/A
HOMEBREW_PREFIX: /opt/homebrew
Homebrew Ruby: 4.0.6 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.6/bin/ruby
CPU: 14-core 64-bit arm_brava
Clang: 21.0.0 build 2100
Git: 2.50.1 => /Applications/Xcode.app/Contents/Developer/usr/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 26.6.2-arm64
CLT: 26.3
Xcode: 26.6
Metal Toolchain: N/A
Rosetta 2: false

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Some installed casks are deprecated or disabled.
You should find replacements for the following casks:
pronterface

Warning: A newer Command Line Tools release is available.
Update them from Software Update in System 设置.

If that doesn't show you any updates, run:
  sudo rm -rf /Library/Developer/CommandLineTools
  sudo xcode-select --install

Alternatively, manually download them from:
  https://developer.apple.com/download/all/.
You should download the Command Line Tools for Xcode 26.3.

Warning: Some installed kegs have no formulae!
This means they were either deleted or installed manually.


You should find replacements for the following formulae:
  git-flow-avh

Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
    git-flow-avh
  icu4c@77

Warning: Your Command Line Tools (CLT) does not support macOS 26.
It is either outdated or was modified.

Please update your Command Line Tools (CLT) or delete it if no updates are available.
Update them from Software Update in System 设置.

If that doesn't show you any updates, run:
  sudo rm -rf /Library/Developer/CommandLineTools
  sudo xcode-select --install

Alternatively, manually download them from:
  https://developer.apple.com/download/all/.
You should download the Command Line Tools for Xcode 26.3.

Warning: The following taps are not trusted:
  wickenico/wailbrew

Homebrew is currently ignoring formulae, casks and commands from these taps because tap trust is required.

Prefer trusting only the specific formulae, casks or commands you need.
Trust installed casks from these taps with:
  brew trust --cask wickenico/wailbrew/wailbrew
Trust other specific formulae and commands with:
  brew trust --formula <user>/<tap>/<formula>
  brew trust --command <user>/<tap>/<command>
Whole-tap trust is broader and includes all current and future formulae,
casks and commands from the listed taps. Trust whole taps with:
  brew trust wickenico/wailbrew
Untap them with:
  brew untap wickenico/wailbrew
To disable trust checks:
  export HOMEBREW_NO_REQUIRE_TAP_TRUST=1
This is not recommended and will be removed in a later release.
For more information, see:
  https://docs.brew.sh/Tap-Trust
This is a Tier 2 configuration:
  https://docs.brew.sh/Support-Tiers#tier-2
You can report issues with Tier 2 configurations to Homebrew/* repositories!
  https://docs.brew.sh/Troubleshooting
Read the above document before opening any issues or PRs.

Description of issue

I replaced a x86 mac by an ARM mac. I installed the OS on the ARM machine from a x86 mac backup. No problem.
I installed Homebrew and some packages a long time ago on the x86 machine, and the ARM machine inherited them. This works as long as Rosetta is supported. But I get OS messages that this is not longer supported in future OS releases. I have found out, that the problem are x86 libraries in /usr/local/lib which are symbolic links to /use/local/Cellar/ - these are x86 versions installed via x86-Homebrew. By the way, I installed other packages with the ARM Homebrew! So, is there a solid way to uninstall x86 packages on ARM?
The current plan is:

1. list all installed ARM packages
2. remove all ARM packages & reboot
3. remove all symbolic links in /usr/local/lib/ which point to /usr/local/Cellar/
4. remove /usr/local/Cellar/ & reboot
5. re-install Homebrew
6. install all packages from step 1

Are there other links? Any other idea how to remove the old stuff?

[SMillerDev]

You can run arch -x86_64 /usr/local/bin/brew bundle dump to get a brewfile that has all your packages. Then you can use that to reinstall everything with arch -arm64 /opt/homebrew/bin/brew bundle install and finally clean up the old install using arch -x86_64 and the script from the FAQ: https://docs.brew.sh/FAQ#how-do-i-uninstall-homebrew

[borisboesler]

Worked!