CD
Cloudflare Developers•2w ago
bkyerv

React SSR on Cloudflare Workers fails due to missing MessageChannel API

Ran into an interesting issue deploying an Astro site using workers (not pages. instead serving static assets using worker): The React renderer fails with MessageChannel is not defined error when trying to do server-side rendering in Workers. 
✘ [ERROR] Deployment failed!

  Failed to publish your Function. Got error: Uncaught ReferenceError: MessageChannel is not defined
    at renderers.mjs:6530:16 in requireReactDomServer_browser_production
    at renderers.mjs:12527:8 in requireServer_browser
    at renderers.mjs:12539:29
✘ [ERROR] Deployment failed!

  Failed to publish your Function. Got error: Uncaught ReferenceError: MessageChannel is not defined
    at renderers.mjs:6530:16 in requireReactDomServer_browser_production
    at renderers.mjs:12527:8 in requireServer_browser
    at renderers.mjs:12539:29
Has anyone found a clean workaround for this?
2 Replies
Chaika
Chaika•2w ago
astro issue and workaround: https://github.com/withastro/astro/issues/12824 workers runtime: https://github.com/cloudflare/workerd/issues/3273
GitHub
React 19 + Cloudflare Adapter -> "Bug: Uncaught ReferenceError: Mes...
Astro Info Astro v5.1.1 Node v22.6.0 System macOS (arm64) Package Manager bun Output server Adapter @astrojs/cloudflare Integrations @astrojs/mdx @astrojs/sitemap @astrojs/tailwind @astrojs/react I...
GitHub
Runtime APIs: MessageChannel · Issue #3273 · cloudflare/workerd
The MessageChannel API is available on node but not CF Workers. This is causing an issue during the deployment of sites using React 19 + Astro + Workers, see facebook/react#31827 and withastro/astr...
bkyerv
bkyervOP•2w ago
Спасибо

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