diff --git a/.changeset/boolean-not-false-2.md b/.changeset/boolean-not-false-2.md
new file mode 100644
index 00000000000..3c47acbecd5
--- /dev/null
+++ b/.changeset/boolean-not-false-2.md
@@ -0,0 +1,5 @@
+----
+'@keystone-6/core': patch
+----
+
+Fix `config.server.cors` type blocking `false` values
diff --git a/.changeset/boolean-not-false.md b/.changeset/boolean-not-false.md
index 0a4d619aa1d..3a7a0a78d20 100644
--- a/.changeset/boolean-not-false.md
+++ b/.changeset/boolean-not-false.md
@@ -1,5 +1,5 @@
 ----
-'@keystone-6/auth': core
+'@keystone-6/core': patch
 ----
 
 Fix `defaultIsFilterable` and `defaultIsOrderable` types blocking `true` values
diff --git a/.changeset/http-async.md b/.changeset/http-async.md
new file mode 100644
index 00000000000..b4ab6555df9
--- /dev/null
+++ b/.changeset/http-async.md
@@ -0,0 +1,5 @@
+---
+'@keystone-6/core': minor
+---
+
+Add `async` to `extendHttpServer`, for `await` on startup
diff --git a/docs/pages/docs/config/config.md b/docs/pages/docs/config/config.md
index 80f37da65cf..fd933484e09 100644
--- a/docs/pages/docs/config/config.md
+++ b/docs/pages/docs/config/config.md
@@ -226,8 +226,8 @@ export default config<TypeInfo>({
     cors: { origin: ['http://localhost:7777'], credentials: true },
     port: 3000,
     maxFileSize: 200 * 1024 * 1024,
-    extendExpressApp: (app, commonContext) => { /* ... */ },
-    extendHttpServer: (httpServer, commonContext, graphQLSchema) => { /* ... */ },
+    extendExpressApp: async (app, commonContext) => { /* ... */ },
+    extendHttpServer: async (httpServer, commonContext, graphQLSchema) => { /* ... */ },
   },
   /* ... */
 });
diff --git a/packages/core/src/lib/server/createExpressServer.ts b/packages/core/src/lib/server/createExpressServer.ts
index 3f52b8e338a..e8566bc3706 100644
--- a/packages/core/src/lib/server/createExpressServer.ts
+++ b/packages/core/src/lib/server/createExpressServer.ts
@@ -1,5 +1,5 @@
 import { createServer, type Server } from 'http'
-import cors, { type CorsOptions } from 'cors'
+import cors from 'cors'
 import { json } from 'body-parser'
 import { expressMiddleware } from '@apollo/server/express4'
 import express from 'express'
@@ -20,8 +20,6 @@ The Admin UI takes a while to build for dev, and is created separately
 so the CLI can bring up the dev server early to handle GraphQL requests.
 */
 
-const DEFAULT_MAX_FILE_SIZE = 200 * 1024 * 1024 // 200 MiB
-
 function formatError (graphqlConfig: GraphQLConfig | undefined) {
   return (formattedError: GraphQLFormattedError, error: unknown) => {
     let debug = graphqlConfig?.debug
@@ -56,9 +54,7 @@ export async function createExpressServer (
   const httpServer = createServer(expressServer)
 
   if (config.server?.cors) {
-    // Setting config.server.cors = true will provide backwards compatible defaults
-    // Otherwise, the user can provide their own config object to use
-    const corsConfig: CorsOptions =
+    const corsConfig =
       typeof config.server.cors === 'boolean'
         ? { origin: true, credentials: true }
         : config.server.cors
@@ -80,13 +76,8 @@ export async function createExpressServer (
     })
   }
 
-  if (config.server?.extendExpressApp) {
-    await config.server.extendExpressApp(expressServer, context)
-  }
-
-  if (config.server?.extendHttpServer) {
-    config.server?.extendHttpServer(httpServer, context, graphQLSchema)
-  }
+  await config.server?.extendExpressApp?.(expressServer, context)
+  await config.server?.extendHttpServer?.(httpServer, context, graphQLSchema)
 
   if (config.storage) {
     for (const val of Object.values(config.storage)) {
@@ -129,8 +120,8 @@ export async function createExpressServer (
   } as ApolloServerOptions<KeystoneContext>
 
   const apolloServer = new ApolloServer({ ...serverConfig })
+  const maxFileSize = config.server?.maxFileSize
 
-  const maxFileSize = config.server?.maxFileSize ?? DEFAULT_MAX_FILE_SIZE
   expressServer.use(graphqlUploadExpress({ maxFileSize }))
   await apolloServer.start()
   expressServer.use(
diff --git a/packages/core/src/system.ts b/packages/core/src/system.ts
index 5e02460a32e..65081be4b56 100644
--- a/packages/core/src/system.ts
+++ b/packages/core/src/system.ts
@@ -25,10 +25,11 @@ export function initConfig (config: KeystoneConfig) {
   config.db.url ??= 'postgres://'
 
   return {
+    ...config,
     types: {
-      path: 'node_modules/.keystone/types.ts'
+      path: 'node_modules/.keystone/types.ts',
+      ...config.types,
     },
-    ...config,
     db: {
       prismaSchemaPath: 'schema.prisma',
       ...config.db,
@@ -38,6 +39,13 @@ export function initConfig (config: KeystoneConfig) {
       ...config.graphql,
     },
     lists: applyIdFieldDefaults(config),
+    server: {
+      cors: false,
+      maxFileSize: 200 * 1024 * 1024, // 200 MiB
+      extendExpressApp: async () => {},
+      extendHttpServer: async () => {},
+      ...config.server,
+    },
   }
 }
 
diff --git a/packages/core/src/types/config/index.ts b/packages/core/src/types/config/index.ts
index cb5684a7d40..8e6916585e2 100644
--- a/packages/core/src/types/config/index.ts
+++ b/packages/core/src/types/config/index.ts
@@ -193,8 +193,8 @@ export type AdminFileToWrite =
 
 // config.server
 export type ServerConfig<TypeInfo extends BaseKeystoneTypeInfo> = {
-  /** Configuration options for the cors middleware. Set to `true` to use core Keystone defaults */
-  cors?: CorsOptions | true
+  /** Configuration options for the cors middleware. Set to `true` to use Keystone's defaults */
+  cors?: boolean | CorsOptions
   /** Maximum upload file size allowed (in bytes) */
   maxFileSize?: number
 
@@ -210,14 +210,14 @@ export type ServerConfig<TypeInfo extends BaseKeystoneTypeInfo> = {
   extendExpressApp?: (
     app: express.Express,
     context: KeystoneContext<TypeInfo>
-  ) => void | Promise<void>
+  ) => MaybePromise<void>
 
   /** extend the node:http server used by Keystone */
   extendHttpServer?: (
     server: Server,
     context: KeystoneContext<TypeInfo>,
     graphqlSchema: GraphQLSchema
-  ) => void
+  ) => MaybePromise<void>
 } & (
   | {
       /** Port number to start the server on. Defaults to process.env.PORT || 3000 */