How to fix fatal: bad revision 'HEAD~5' in Git

Make sure you're using the correct syntax for revision specifiers:

# Correct: using tilde (~) for ancestor commits
git revert HEAD~5

# Wrong: using hyphen (-) instead of tilde
git revert HEAD-5  # This causes "bad revision" error

The tilde (~) followed by a number means "N commits back following first parents." Using a hyphen is a common mistake.

Count the commits in your repository to ensure you're not referencing beyond the available history:

# Count total commits on current branch
git rev-list --count HEAD

# View recent commit history
git log --oneline | head -10

If you only have 3 commits and try git revert HEAD~5, you'll get a bad revision error because that commit doesn't exist.

If you're working with a shallow clone (common in CI/CD pipelines), fetch the full history:

# Convert shallow clone to full clone
git fetch --unshallow

# Alternative: fetch specific depth
git fetch --depth=100

For GitHub Actions, modify your checkout step:

- uses: actions/checkout@v4
  with:
    fetch-depth: 0  # Fetches all history for all branches

For GitLab CI, set in your .gitlab-ci.yml:

variables:
  GIT_DEPTH: 0  # Full clone

If the commit exists on the remote but not locally, fetch it:

# Fetch all branches and tags
git fetch --all

# Fetch a specific branch
git fetch origin main

# Verify the commit now exists
git cat-file -t <commit-hash>  # Should output "commit"

If you're trying to revert a commit from a different branch, make sure that branch is fetched first.

Short commit hashes can be ambiguous or mistyped. Use the full 40-character hash:

# Get the full hash of a commit
git rev-parse HEAD~5

# Then use the full hash for the revert
git revert <full-40-char-hash>

You can also use git log to copy the exact hash you need:

git log --oneline -10
# Pick the commit hash from the output

Before running the revert, confirm the revision is valid:

# Check if revision exists and show commit info
git show HEAD~5 --no-patch

# Or check if a specific hash exists
git cat-file -e <commit-hash> && echo "Commit exists"

If these commands fail, the commit doesn't exist in your local repository and you need to fetch it first.

If you're trying to revert to a previous state but can't find the commit, use reflog:

# Show all recent HEAD movements
git reflog

# Find the commit you want and use its reference
git revert HEAD@{3}  # Reverts the state from 3 operations ago

The reflog shows every position HEAD has been in, even for commits that might not be reachable through normal history.