❯ brew update \&\& brew upgrade \&\& brew cleanup

`❯ brew update \&\& brew upgrade \&\& brew cleanup`

==> Updating Homebrew…
fatal: It seems that there is already a rebase-merge directory, and
I wonder if you are in the middle of another rebase. If that is the
case, please try
git rebase (–continue | –abort | –skip)
If that is not the case, please
rm -fr “.git/rebase-merge”
and run me again. I am stopping in case you still have something
valuable there.

The error you’re seeing during brew update — “fatal: It seems that there is already a rebase-merge directory…” — means a previous Homebrew git rebase operation was interrupted and left temporary files behind, blocking new updates.

How to Fix It

Check for and remove the stray rebase directory:
- For Intel Macs:

find /usr/local/Homebrew -name "rebase-merge"

- For Apple Silicon (M1/M2/M3):

find /opt/Homebrew -name "rebase-merge"

If a directory like /opt/Homebrew/Library/Taps/homebrew/homebrew-core/.git/rebase-merge appears, remove it:

rm -rf /opt/Homebrew/Library/Taps/homebrew/homebrew-core/.git/rebase-merge

After that, retry:

brew update && brew upgrade

This resolves the issue for most users.^1

If the rebase is still active, abort it:
If you prefer not to delete anything immediately, you can instead run:

cd /opt/homebrew
git rebase --abort
brew update

This safely cancels the stuck rebase and resumes normal operation.^1

Alternative recovery (safer reset command):
If both fail or the problem returns:

brew update-reset

This resets Homebrew’s git repositories to a clean state, ensuring no leftover rebase data remains.^2

Why It Happens

Homebrew uses Git internally to manage its repositories. Updates sometimes interrupt mid-rebase (e.g., due to network loss or macOS sleep), leaving .git/rebase-merge folders behind. Future updates stop to prevent data loss.^2

Summary of Fixes

Situation	Command to Use	Notes
Stale rebase-merge directory	`rm -rf $(find /opt/homebrew -name "rebase-merge")`	Most common fix ^1
Ongoing rebase	`git rebase --abort && brew update`	Use if rebase was started but unfinished ^1
Persistent problems	`brew update-reset`	Performs a full git restore of Homebrew ^2

After applying one of these, your brew update && brew upgrade && brew cleanup chain should work normally again.
^10 ^12 ^14 ^16 ^18 ^20 ^4 ^6 ^8

⁂