TL;DR

Apollo Client now handles Relay (data fetching) multipart subscriptions more reliably and significantly improves cache write performance, especially for streamed data.

Fixes Worth Knowing

• Relay multipart subscriptions now correctly handle serialization failures, preventing unnecessary network requests.
• Cache writes are faster, and streamed data overwrites existing lists as expected, resolving unexpected merging behavior. (AST = Abstract Syntax Tree)

TL;DR

Apollo Client now supports custom scalars (data types beyond standard GraphQL) with new code generation features, simplifying configuration of the InMemoryCache for complex data handling.

New

• GraphQL Codegen plugin generates configuration for custom scalars, streamlining InMemoryCache setup.
• The new plugin generates both inputObjects and scalarTypePolicies for comprehensive custom scalar support.

Before You Upgrade

Update your codegen.ts file to include the @apollo/client-graphql-codegen/custom-scalars plugin and configure it according to the documentation to leverage the new features.

TL;DR

Apollo Client’s GraphQL Codegen integration now supports the latest major versions of the GraphQL Codegen package (code generation tool), ensuring compatibility and access to new features in that ecosystem.

New

GraphQL Codegen support updated to latest major.

TL;DR

Apollo Client now supports custom scalars (data types like dates or currencies) with improved type safety and serialization, simplifying complex data handling in your GraphQL applications.

New

• Custom Scalar Support: Define and use custom scalars within InMemoryCache for parsing, serializing, and validating data.
• Automatic Scalar Serialization: Variables containing custom scalar values are now automatically serialized for network requests and cache operations.
• Input Object Configuration: Specify where nested scalar fields are found within input objects for more complex data structures.

Fixes Worth Knowing

• Custom scalars are now correctly handled during cache reads, writes, and restoration using cache.extract() and cache.restore().

TL;DR

Apollo Client now correctly silences deprecation warnings, even when used in different parts of your application, improving console clarity.

Fixes Worth Knowing

Deprecation warnings are now consistently muted when globally disabled, resolving issues where warnings reappeared unexpectedly.

Before You Upgrade

If you globally muted deprecation warnings, verify they remain silenced after upgrading.

TL;DR

Apollo Client now supports generating resolver types for LocalState (client-side data management) using a new GraphQL Codegen plugin, streamlining type safety for local data.

Breaking

• Codemod Required: A codemod is available to update import paths from Apollo Client v3 to v4. Run npx @apollo/client-codemod-migrate-3-to-4 --parser tsx ./src/**/*.{ts,tsx}.
• gql Import: gql is no longer exported from @apollo/client/react; import it directly from @apollo/client.
• ApolloClient Type: The TCacheShape type argument has been removed from ApolloClient usages.

New

• Local State Codegen Plugin: Generate resolver types for LocalState using the @apollo/client-graphql-codegen/local-state plugin.
• Comprehensive Codemod: A codemod automates several key migration steps, including updating HttpLink configuration and LocalState setup.

Fixes Worth Knowing

• Corrected an issue where networkStatus wasn’

TL;DR

Apollo Client v4 migration is now easier with a new codemod (code modification tool) that automates many upgrade steps, including configuration and import updates.

Breaking

• uri, headers, and credentials must be moved to the link option and use a new HttpLink instance. (Configuration change)
• name and version are now part of clientAwareness. (Configuration change)
• typeDefs and fragmentMatcher options are removed; use localState with a LocalState instance instead. (Configuration change)
• disableNetworkFetches is renamed to prioritizeCacheValues. (Configuration change)
• Legacy import paths (e.g., @apollo/client/main.cjs) are updated to new entry points. (Import change)

New

No new features.

Fixes Worth Knowing

No fixes worth knowing.

Before You Upgrade

Run the clientSetup codemod step to automate most configuration changes before updating to Apollo Client v4.

TL;DR

Apollo Client is preparing for version 4.0 with deprecation warnings on older APIs, helping developers identify code that will require updates.

Breaking

• APIs used with client.query, client.mutate, and client.subscribe are deprecated (methods for fetching/modifying data).
• Using a standby fetch policy with client.query now triggers a warning (controls caching behavior).

Before You Upgrade

Review console warnings for deprecated API usage and plan migration paths to ensure compatibility with Apollo Client 4.0.