yarn --frozen-lockfile Outdated in CI - Fix Lockfile Out of Sync

yarn install --frozen-lockfile (Yarn Classic) fails if installing would change yarn.lock. In CI that guards reproducibility, so the error means your lockfile does not match package.json.

What this error means

The CI install step fails saying your lockfile needs to be updated but --frozen-lockfile prevented this. Locally yarn install succeeds because it is allowed to write yarn.lock.

error Your lockfile needs to be updated, but yarn was run with
`--frozen-lockfile`.
error Found incompatibilities between package.json and yarn.lock.

Common causes

package.json was changed without updating yarn.lock

A dependency edit landed without re-running yarn, so the committed lockfile no longer matches the manifest.

The lockfile was generated by a different yarn version

A different Yarn produced a lockfile shape CI does not accept as frozen.

How to fix it

Update and commit the lockfile

1. Run yarn install locally to regenerate yarn.lock.
2. Commit the updated lockfile so CI matches it.

yarn install
git add yarn.lock
git commit -m "Update yarn.lock"

How to prevent it

• Commit yarn.lock with every dependency change, pin the Yarn version, and keep --frozen-lockfile in CI so drift is caught before merge.

Related guides