Composer "lock file is not up to date with the latest changes in composer.json" in CI

composer validate compares the content hash stored in composer.lock against the current composer.json. When they differ, it warns the lock is stale and that an install would pull outdated dependencies.

What this error means

composer validate fails (or warns and exits non-zero with --strict) with "The lock file is not up to date with the latest changes in composer.json. You may be getting outdated dependencies. Run update to update them."

composer

./composer.json is valid, but with a few warnings
See https://getcomposer.org/doc/04-schema.md for details on the schema
# Lock file warning
The lock file is not up to date with the latest changes in composer.json.
You may be getting outdated dependencies. Run update to update them.

Common causes

The content hash drifted after a manifest edit

A dependency was added or its constraint changed in composer.json, but composer.lock was not regenerated, so the stored hash no longer matches.

validate --strict treats the warning as a failure

CI runs composer validate --strict, which turns the lock-staleness warning into a non-zero exit and fails the step.

How to fix it

Refresh the lock hash

Run composer update --lock to update the stored hash without changing resolved versions.
Commit the updated composer.lock.
Re-run composer validate to confirm it passes.

Terminal

composer update --lock

Run validate before install in CI

Catch drift at the start of the job, before a stale install silently pulls outdated dependencies.