diff --git a/.changeset/proud-trains-wonder.md b/.changeset/proud-trains-wonder.md
new file mode 100644
index 0000000000..0e437cfad6
--- /dev/null
+++ b/.changeset/proud-trains-wonder.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Add useful warning when deprecated options are still used.
diff --git a/packages/astro/src/core/build/index.ts b/packages/astro/src/core/build/index.ts
index 013d83a5bc..5280e69e3d 100644
--- a/packages/astro/src/core/build/index.ts
+++ b/packages/astro/src/core/build/index.ts
@@ -242,6 +242,10 @@ class AstroBuilder {
 					'The option `build.split` won\'t take effect, because `output` is not `"server"` or `"hybrid"`.'
 				);
 			}
+			this.logger.warn(
+				'configuration',
+				'The option `build.split` is deprecated. Use the adapter options.'
+			);
 		}
 		if (config.build.excludeMiddleware === true) {
 			if (config.output === 'static') {
@@ -250,14 +254,10 @@ class AstroBuilder {
 					'The option `build.excludeMiddleware` won\'t take effect, because `output` is not `"server"` or `"hybrid"`.'
 				);
 			}
-		}
-
-		if (config.build.split === true) {
-			if (config.output !== 'server') {
-				throw new Error(
-					'The option `build.split` can only be used when `output` is set to `"server"`.'
-				);
-			}
+			this.logger.warn(
+				'configuration',
+				'The option `build.excludeMiddleware` is deprecated. Use the adapter options.'
+			);
 		}
 	}