@langchain/core migration guide
Plan an @langchain/core upgrade: predict method removals in 1.0, selected later type changes, release guides and scan limits.
Upgrading @langchain/core can change model calls, imports and the types shared by LangChain.js packages. Start with the 1.0 migration if you still use the legacy prediction methods. For a later 1.x target, read the listed releases between your installed version and that target.
Choose your migration path
- Move to core 1.0: predict and predictMessages were removed from chat models. Move to invoke and review its return value. The release also removes legacy subpaths and named exports; the guide separates possible assisted fixes from report-only removals.
- Review later 1.x type changes: Use the release pages below to check the particular exported types your code names. A type-reference finding needs review of the changed member before you decide that an edit is needed.
Check your upgrade
Check your installed version in the manifest and lockfile, then read the release pages your upgrade crosses. Run npx emendant scan to find supported changes in TypeScript and JavaScript source without editing your files. Use npx emendant fix --dry-run to preview deterministic patches where available. The preview does not install dependencies, run your checks or call a model. Assisted patches need a named model provider and a fix run without --dry-run. After updating dependencies, run your typecheck and tests and review the patch grades in the fix guide.
Coverage and limits
These pages cover selected @langchain/core changes. They do not cover every LangChain integration or prove that companion packages are compatible. Check langchain separately and review the upstream migration sources linked from each release.
The linked release pages list covered findings, possible fixes and tagged sources. A clean scan does not prove that every migration step is complete. Read the supported projects guide for the scan's scope.
The LangChain.js migration guide covers @langchain/core and says which of these release pages to read for your upgrade.
@langchain/core release pages
- @langchain/core 1.x breaking changes: 1.1.7 to 1.2.18
11 releases, 1.1.7 to 1.2.18, released 18 December 2025 to 15 October 2026. 39 breaking, 2 deprecations. - @langchain/core 1.0.0: predict methods removed
@langchain/core 1.0.0, released 17 October 2025. 28 breaking, 29 deprecations.
Releases without a page here may still be in the feed. Run emendant feed status to see what your snapshot holds.