TypeScript 6.0 is a transition release that prepares projects for the next generation of the compiler. The practical impact is that teams should review deprecated settings, module behavior, and assumptions that have survived unnoticed in older configurations.
The safest approach is incremental: upgrade tooling first, record every compiler change, and keep application behavior separate from configuration cleanup.
Audit the compiler configuration
Begin with tsconfig files across the repository, including test, build, and package-level configurations. Remove settings that are no longer effective, document inherited configuration, and check whether module resolution matches the actual runtime and bundler.
- Run the compiler with no emit before changing application code.
- Upgrade editor tooling and CI to the same TypeScript version.
- Treat new errors as migration tasks, not reasons to disable strictness.
Keep the migration reviewable
Use small pull requests grouped by configuration, shared types, and application areas. This makes regressions easier to isolate and avoids a single upgrade branch that becomes too large to review or safely roll back.
TypeScript upgrades are most valuable when they leave the codebase clearer than before. Use 6.0 as a chance to remove configuration debt and establish a predictable path toward TypeScript 7.