Vercel now blocks production deployments for microfrontend default apps that are missing microfrontends.json from their build outputs. The check is enabled automatically, no opt-in required, for any project enrolled in Vercel Microfrontends and designated as the default app in a Microfrontends group.
The failure condition is specific: if microfrontends.json is absent at build output time, the deployment is stopped before it reaches production. The most common trigger is manually promoting a deployment from an older branch that predates the Microfrontends configuration. The check resolves on the next deployment once the file is present.
This joins Vercel's existing suite of native deployment checks alongside lint and typecheck. Behavior can be adjusted per-project in Build and Deployment Settings. The original changelog entry is worth reading for the exact check naming and how it surfaces in the deployment checks UI alongside other blocking checks.
[READ ORIGINAL →]