Svelte 5.56 and TypeScript 6: The peerDependency Change That Breaks Your Setup

The June 2026 Svelte update introduces TypeScript 6 across its toolchain, including a peerDependency change that silently breaks setups using a custom language server path. Five packages updated in sync to support TypeScript 6, which offers 40-60% faster incremental builds and new features. Developers must run specific commands to fix broken configurations.

The June 2026 Svelte update looks like a routine version bump. It is not. TypeScript 6 is now the standard across Svelte’s entire toolchain — and it shipped with a peerDependency change that silently breaks setups using a custom language server path. Here is what changed, who is affected, and what to run right now. TypeScript 6 Lands Across the Toolchain Five packages updated in sync to support TypeScript 6: The upgrade is well-motivated. TypeScript 6 delivers 40–60% faster incremental builds, more precise inference on private class fields, and the using keyword for automatic resource management. Keeping Svelte tools locked … The post