Your deployment is failing because Railway runs yarn install --check-cache, and Yarn detects that your yarn.lock is out of sync with the project (or workspace) configuration, which is not allowed in that mode. This usually happens when the lockfile doesn’t match the actual dependencies, the workspace root is misconfigured, or the service root directory in Railway points to a subfolder that doesn’t align with where yarn.lock lives. As a result, the build fails before deployment even starts. To fix this, make sure the Railway service root directory is correct, ensure there is a single valid yarn.lock at the workspace root, regenerate it locally (rm -rf node_modules yarn.lock && yarn install), commit the updated lockfile, and verify that yarn install --immutable succeeds locally before redeploying.