Git Troubleshooting Skill

This skill provides comprehensive guidance on diagnosing and resolving git issues, recovering from mistakes, fixing corrupted repositories, and handling common error scenarios.

When to Use

Activate this skill when:

• Encountering git error messages
• Recovering lost commits or branches
• Fixing corrupted repositories
• Resolving detached HEAD state
• Handling botched merges or rebases
• Diagnosing repository issues
• Recovering from force push
• Fixing authentication problems

Recovering Lost Commits

Using Reflog

# View reflog (local history of HEAD)
git reflog

# View reflog for specific branch
git reflog show branch-name

# Output example:
# abc123 HEAD@{0}: commit: feat: add authentication
# def456 HEAD@{1}: commit: fix: resolve bug
# ghi789 HEAD@{2}: reset: moving to HEAD~1

# Recover lost commit
git cherry-pick abc123

# Or create branch from lost commit
git branch recovered-branch abc123

# Or reset to lost commit
git reset --hard abc123

Finding Dangling Commits

# Find all unreachable objects
git fsck --lost-found

# Output:
# dangling commit abc123
# dangling blob def456

# View dangling commit
git show abc123

# Recover dangling commit
git branch recovered abc123

# Or merge it
git merge abc123

Recovering Deleted Branch

# Find branch commit in reflog
git reflog

# Look for branch deletion:
# abc123 HEAD@{5}: checkout: moving from feature-branch to main

# Recreate branch
git branch feature-branch abc123

# Or if branch was merged before deletion
git log --all --oneline | grep "feature"
git branch feature-branch def456

Recovering After Reset

# After accidental reset --hard
git reflog

# Find commit before reset:
# abc123 HEAD@{0}: reset: moving to HEAD~5
# def456 HEAD@{1}: commit: last good commit

# Restore to previous state
git reset --hard def456

# Or create recovery branch
git branch recovery def456

Resolving Detached HEAD

Understanding Detached HEAD

# Detached HEAD state occurs when:
git checkout abc123
git checkout v1.0.0
git checkout origin/main

# HEAD is not attached to any branch

Recovering from Detached HEAD

# Check current state
git status
# HEAD detached at abc123

# Option 1: Create new branch
git checkout -b new-branch-name

# Option 2: Return to previous branch
git checkout main

# Option 3: Reattach HEAD to branch
git checkout -b temp-branch
git checkout main
git merge temp-branch

# If you made commits in detached HEAD:
git reflog
# Find the commits
git branch recovery-branch abc123

Preventing Detached HEAD

# Instead of checking out tag directly
git checkout -b release-v1.0 v1.0.0

# Instead of checking out remote branch
git checkout -b local-feature origin/feature-branch

# Check if HEAD is detached
git symbolic-ref -q HEAD && echo "attached" || echo "detached"

Fixing Merge Conflicts

Understanding Conflict Markers

<<<<<<< HEAD (Current Change)
int result = add(a, b);
||||||| merged common ancestors (Base)
int result = sum(a, b);
=======
int sum = calculate(a, b);
>>>>>>> feature-branch (Incoming Change)

Basic Conflict Resolution

# When merge conflict occurs
git status
# both modified: file.go

# View conflict
cat file.go

# Option 1: Keep ours (current branch)
git checkout --ours file.go
git add file.go

# Option 2: Keep theirs (incoming branch)
git checkout --theirs file.go
git add file.go

# Option 3: Manual resolution
# Edit file.go to resolve conflicts
git add file.go

# Complete merge
git commit

Aborting Operations

# Abort merge
git merge --abort

# Abort rebase
git rebase --abort

# Abort cherry-pick
git cherry-pick --abort

# Abort revert
git revert --abort

# Abort am (apply mailbox)
git am --abort

Complex Conflict Resolution

# Use merge tool
git mergetool

# View three-way diff
git diff --ours
git diff --theirs
git diff --base

# Show conflicts with context
git diff --check

# List conflicted files
git diff --name-only --diff-filter=U

# After resolving all conflicts
git add .
git commit

Fixing Botched Rebase

Recovering from Failed Rebase

# Abort current rebase
git rebase --abort

# Find state before rebase
git reflog
# abc123 HEAD@{1}: rebase: checkout main

# Return to pre-rebase state
git reset --hard HEAD@{1}

# Alternative: use ORIG_HEAD
git reset --hard ORIG_HEAD

Rebase Conflicts

# During rebase conflict
git status
# both modified: file.go

# Resolve conflicts
# Edit file.go
git add file.go
git rebase --continue

# Skip problematic commit
git rebase --skip

# Edit commit during rebase
git commit --amend
git rebase --continue

Rebase onto Wrong Branch

# Find original branch point
git reflog

# Reset to before rebase
git reset --hard HEAD@{5}

# Rebase onto correct branch
git rebase correct-branch

Repository Corruption

Detecting Corruption

# Check repository integrity
git fsck --full

# Check connectivity
git fsck --connectivity-only

# Verify pack files
git verify-pack -v .git/objects/pack/*.idx

Fixing Corrupted Objects

# Remove corrupted object
rm .git/objects/ab/cd1234...

# Try to recover from remote
git fetch origin

# Rebuild object database
git gc --prune=now

# Aggressive cleanup
git gc --aggressive --prune=now

Fixing Index Corruption

# Remove corrupted index
rm .git/index

# Rebuild index
git reset

# Or reset to HEAD
git reset --hard HEAD

Recovering from Bad Pack File

# Unpack corrupted pack
git unpack-objects < .git/objects/pack/pack-*.pack

# Remove corrupted pack
rm .git/objects/pack/pack-*

# Repack repository
git repack -a -d

# Verify integrity
git fsck --full

Fixing References

Corrupted Branch References

# View all references
git show-ref

# Manual reference fix
echo "abc123def456" > .git/refs/heads/branch-name

# Or use update-ref
git update-ref refs/heads/branch-name abc123

# Delete corrupted reference