How to fix fatal: bad object abc1234 in Git

# Run fsck to find all bad objects
git fsck --full

# Check what refs exist
git show-ref

# Look at the specific error - if it mentions a path like
# refs/remotes/origin/HEAD, check that file:
cat .git/refs/remotes/origin/HEAD

# Auto-detect and update the remote HEAD
git remote set-head origin --auto

# If that fails, manually set it to the correct branch
git remote set-head origin main

# Prune stale remote-tracking references
git remote prune origin

# Verify the fix
git gc

# First, check what the reference contains
cat .git/refs/remotes/origin/HEAD

# If it shows an invalid hash (all zeros, truncated, or garbled):
# Delete the corrupted reference
git update-ref -d refs/remotes/origin/HEAD

# For other corrupted refs, use the same pattern:
git update-ref -d "<corrupted-ref-path>"

# Then verify and fetch fresh data
git fetch origin
git gc

# Fetch all objects from all remotes
git fetch --all

# For shallow clones, unshallow to get full history
git fetch --unshallow

# Fetch with full object download
git fetch --refetch

# If specific branches are problematic:
git fetch origin main:refs/remotes/origin/main

# View reflog entries
git reflog

# Check all reflogs for the missing hash
git reflog --all | grep <partial-hash>

# If found, the object still exists - create a reference to prevent pruning
git branch recovered-<hash> <full-hash>

# Unpack all pack files (creates loose objects)
git unpack-objects < .git/objects/pack/*.pack

# Remove old pack files
rm .git/objects/pack/*

# Repack the repository
git repack -a -d

# Run gc again
git gc

# Clone to a new directory
git clone <remote-url> repo-fresh

# If you have uncommitted changes, copy them over
# From the corrupted repo:
rsync -av --exclude='.git' ./ ../repo-fresh/

# Or on Windows:
xcopy /E /I /EXCLUDE:.git . ..\repo-fresh

# Switch to fresh clone
cd ../repo-fresh
git status