/compare/yarn/yarn-classic-vs-yarn-berry
Yarn 1 (Classic) vs Yarn 4 (Berry): differences and command mapping
- tool
- Yarn
- compares
- Yarn 1 (Classic) vs Yarn 2+ (Berry, today Yarn 4)
Yarn 1 (Classic, 1.22.x) only receives critical fixes; new features land in Yarn 2 and later, the codebase called Berry (current major: Yarn 4). Berry is installed per project and pinned with the packageManager field (Corepack), is configured in .yarnrc.yml, can install without node_modules (Plug'n'Play) and renames several commands. Both read package.json the same way, so most projects migrate by running yarn set version stable and yarn install.
Side by side
| Criterion | Yarn 1 (Classic) | Yarn 2+ (Berry) |
|---|---|---|
| Installation | Global: npm install -g yarn | Per project: corepack enable, then yarn set version stable (writes packageManager) |
| node_modules | Always, hoisted like npm | nodeLinker: pnp (no node_modules), node-modules or pnpm |
| Config file | .yarnrc and .npmrc | .yarnrc.yml only (npmRegistryServer, npmAuthToken...) |
| Lockfile | yarn.lock (v1 format) | yarn.lock with __metadata (YAML), not readable by Yarn 1 |
| CI install | yarn install --frozen-lockfile | yarn install --immutable (default when CI is detected) |
| Messages | error / warning / info | Coded messages (YN0000...) |
| Run a package once | npx | yarn dlx PACKAGE |
| Plugins | none | yarn plugin import; many features are plugins |
| Maintenance | Critical fixes only | Active development |
Command mapping
| Yarn 1 | Yarn 2+ |
|---|---|
| yarn install --frozen-lockfile | yarn install --immutable |
| yarn upgrade PACKAGE | yarn up PACKAGE |
| yarn upgrade-interactive | yarn upgrade-interactive (built in since Yarn 4) |
| yarn install --production | yarn workspaces focus --production |
| yarn global add PACKAGE | removed: use yarn dlx PACKAGE or a project dependency |
| yarn create APP | yarn create APP (runs through yarn dlx) |
| yarn workspaces run build | yarn workspaces foreach -A run build |
| yarn why PACKAGE | yarn why PACKAGE |
Migrating a project
corepack enable
yarn set version stable # downloads Yarn 4 and writes packageManager to package.json
echo "nodeLinker: node-modules" >> .yarnrc.yml # optional: keep a node_modules folder
yarn install # rewrites yarn.lock in the new formatKeeping nodeLinker: node-modules makes the switch transparent for tools that expect node_modules; Plug'n'Play can be adopted later. Commit .yarnrc.yml, yarn.lock and the packageManager field, and add .yarn/cache, .yarn/install-state.gz and .pnp.* to .gitignore unless you want zero-installs.