Chromatic "git history not found" / shallow clone in CI

By Kaveh Alemi·Latchkey

Chromatic walks git history to find the ancestor commit that produced the baseline snapshots. A shallow clone (the default fetch-depth: 1) hides ancestors, so Chromatic cannot establish a baseline and warns or fails.

What this error means

The chromatic step reports it could not find the baseline commit or that the git history is incomplete, often advising a full clone with fetch-depth 0.

Chromatic only has access to the current commit and cannot find baseline builds.
This usually happens when the repository is checked out with a shallow clone.
Set fetch-depth: 0 on actions/checkout.

Common causes

actions/checkout uses a shallow clone by default

The default fetch-depth: 1 fetches only the latest commit, so Chromatic cannot walk back to the baseline commit.

A squashed or rebased branch lost the baseline ancestor

History rewrites can detach the branch from the commit Chromatic recorded the baseline against, leaving no common ancestor in a shallow clone.

How to fix it

Fetch full history in checkout

1. Set fetch-depth: 0 on the checkout step.
2. Run the chromatic step after the full-history checkout.
3. Re-run so Chromatic can resolve the baseline.

- uses: actions/checkout@v4
  with:
    fetch-depth: 0
- uses: chromaui/action@latest
  with:
    projectToken: ${{ secrets.CHROMATIC_PROJECT_TOKEN }}

Unshallow before Chromatic if needed

If you cannot change checkout, deepen the existing clone before running Chromatic.

git fetch --unshallow || true

How to prevent it

• Use fetch-depth: 0 for any tool that reads git history, including Chromatic.
• Keep the Chromatic job on the same checkout that has full history.
• Avoid rewriting history on branches that carry Chromatic baselines.

Frequently asked questions

Related guides

References

• Node.js documentation
• npm CLI documentation
• GitHub Actions documentation