astro/.changeset/tricky-candles-suffer.md

astro	@astrojs/vercel
major	minor

The build.split and build.excludeMiddleware configuration options are deprecated and have been replaced by options in the adapter config.

If your config includes the build.excludeMiddleware option, replace it with edgeMiddleware in your adapter options:

import { defineConfig } from "astro/config";
import vercel from "@astrojs/vercel/serverless";

export default defineConfig({
     build: {
-        excludeMiddleware: true
     },
     adapter: vercel({
+        edgeMiddleware: true
     }),
});

If your config includes the build.split option, replace it with functionPerRoute in your adapter options:

import { defineConfig } from "astro/config";
import vercel from "@astrojs/vercel/serverless";

export default defineConfig({
     build: {
-        split: true
     },
     adapter: vercel({
+        functionPerRoute: true
     }),
});