Migrate to Ant Design v6: zeroRuntime & CSS Variables
Why Ant Design v6 matters Ant Design v6 is a technical, performance-first upgrade. It modernizes the styling engine around CSS variables, raises the minimum React version to 18, and introduces a zeroRuntime mode that can dramatically reduce runtime cost and bundle size. If you maintain a production UI built on Ant Design, planning an Ant Design v6 migration is a great opportunity to remove legacy…
Ant Design v6 is a performance-focused upgrade that introduces CSS variables, raises the minimum React version to 18, and offers a zeroRuntime mode for smaller bundles and faster page startup. Before migrating, ensure you're on React 18+, upgrade @ant-design/icons to v6, and remove any React 19 patches. Confirm your browser support, as v6 uses CSS variables and no longer supports IE.
A common runtime issue to watch for is undefined themes, which can cause ConfigProvider to read tokens unexpectedly, leading to styles failing and components remounting. To avoid this, normalize undefined themes to an empty object. The zeroRuntime mode can significantly improve performance by reducing runtime cost and bundle size, but it has trade-offs, particularly for apps that rely on dynamic runtime token swapping.
It requires manual import of component CSS or extraction using @ant-design/static-style-extract. Be mindful of DOM changes and audit your CSS selectors to avoid breakages. Overall, plan a thorough migration checklist to ensure a smooth transition to Ant Design v6.
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