diff --git a/.changeset/popular-deers-whisper.md b/.changeset/popular-deers-whisper.md
new file mode 100644
index 00000000000..baecaca8289
--- /dev/null
+++ b/.changeset/popular-deers-whisper.md
@@ -0,0 +1,5 @@
+---
+"@whatwg-node/server": patch
+---
+
+Fix for undefined server context parts
diff --git a/packages/server/src/createServerAdapter.ts b/packages/server/src/createServerAdapter.ts
index 601c0b7c613..bd87608a98b 100644
--- a/packages/server/src/createServerAdapter.ts
+++ b/packages/server/src/createServerAdapter.ts
@@ -39,12 +39,7 @@ import {
 } from './uwebsockets.js';
 
 async function handleWaitUntils(waitUntilPromises: Promise<unknown>[]) {
-  const waitUntils = await Promise.allSettled(waitUntilPromises);
-  waitUntils.forEach(waitUntil => {
-    if (waitUntil.status === 'rejected') {
-      console.error(waitUntil.reason);
-    }
-  });
+  await Promise.allSettled(waitUntilPromises);
 }
 
 type RequestContainer = { request: Request };
@@ -58,14 +53,6 @@ function isRequestAccessible(serverContext: any): serverContext is RequestContai
   }
 }
 
-function addWaitUntil(serverContext: any, waitUntilPromises: Promise<unknown>[]): void {
-  serverContext['waitUntil'] = function (promise: Promise<void> | void) {
-    if (promise != null) {
-      waitUntilPromises.push(promise);
-    }
-  };
-}
-
 export interface ServerAdapterOptions<TServerContext> {
   plugins?: ServerAdapterPlugin<TServerContext>[];
   fetchAPI?: Partial<FetchAPI>;
@@ -206,8 +193,10 @@ function createServerAdapter<
     const defaultServerContext = {
       req: nodeRequest,
       res: serverResponse,
+      waitUntil(cb: Promise<unknown>) {
+        waitUntilPromises.push(cb.catch(err => console.error(err)));
+      },
     };
-    addWaitUntil(defaultServerContext, waitUntilPromises);
     let response$: Response | Promise<Response> | undefined;
     try {
       response$ = handleNodeRequest(nodeRequest, defaultServerContext as any, ...ctx);
@@ -234,10 +223,15 @@ function createServerAdapter<
     const defaultServerContext = {
       res,
       req,
+      waitUntil(cb: Promise<unknown>) {
+        waitUntilPromises.push(cb.catch(err => console.error(err)));
+      },
     };
-    addWaitUntil(defaultServerContext, waitUntilPromises);
+    const filteredCtxParts = ctx.filter(partCtx => partCtx != null);
     const serverContext =
-      ctx.length > 0 ? completeAssign(defaultServerContext, ...ctx) : defaultServerContext;
+      filteredCtxParts.length > 0
+        ? completeAssign(defaultServerContext, ...ctx)
+        : defaultServerContext;
     const request = getRequestFromUWSRequest({
       req,
       res,
@@ -277,23 +271,32 @@ function createServerAdapter<
     if (!event.respondWith || !event.request) {
       throw new TypeError(`Expected FetchEvent, got ${event}`);
     }
-    const serverContext = ctx.length > 0 ? Object.assign({}, event, ...ctx) : event;
+    const filteredCtxParts = ctx.filter(partCtx => partCtx != null);
+    const serverContext =
+      filteredCtxParts.length > 0
+        ? completeAssign({}, event, ...filteredCtxParts)
+        : isolateObject(event);
     const response$ = handleRequest(event.request, serverContext);
     event.respondWith(response$);
   }
 
   function handleRequestWithWaitUntil(request: Request, ...ctx: Partial<TServerContext>[]) {
-    const serverContext = ctx.length > 1 ? completeAssign(...ctx) : isolateObject(ctx[0]);
-    if (serverContext.waitUntil == null) {
-      const waitUntilPromises: Promise<void>[] = [];
-      addWaitUntil(serverContext, waitUntilPromises);
-      const response$ = handleRequest(request, serverContext);
-      if (waitUntilPromises.length > 0) {
-        return handleWaitUntils(waitUntilPromises).then(() => response$);
-      }
-      return response$;
+    const filteredCtxParts: any[] = ctx.filter(partCtx => partCtx != null);
+    let waitUntilPromises: Promise<void>[] | undefined;
+    const serverContext =
+      filteredCtxParts.length > 1
+        ? completeAssign(...filteredCtxParts)
+        : isolateObject(
+            filteredCtxParts[0],
+            filteredCtxParts[0] == null || filteredCtxParts[0].waitUntil == null
+              ? (waitUntilPromises = [])
+              : undefined,
+          );
+    const response$ = handleRequest(request, serverContext);
+    if (waitUntilPromises?.length) {
+      return handleWaitUntils(waitUntilPromises).then(() => response$);
     }
-    return handleRequest(request, serverContext);
+    return response$;
   }
 
   const fetchFn: ServerAdapterObject<TServerContext>['fetch'] = (
diff --git a/packages/server/src/utils.ts b/packages/server/src/utils.ts
index 370adff63f6..7f8bbc00ec3 100644
--- a/packages/server/src/utils.ts
+++ b/packages/server/src/utils.ts
@@ -446,6 +446,7 @@ export function handleErrorFromRequestHandler(error: any, ResponseCtor: typeof R
 
 export function isolateObject<TIsolatedObject extends object>(
   originalCtx: TIsolatedObject,
+  waitUntilPromises?: Promise<unknown>[],
 ): TIsolatedObject {
   if (originalCtx == null) {
     return {} as TIsolatedObject;
@@ -454,6 +455,11 @@ export function isolateObject<TIsolatedObject extends object>(
   const deletedProps = new Set<string | symbol>();
   return new Proxy(originalCtx, {
     get(originalCtx, prop, receiver) {
+      if (waitUntilPromises != null && prop === 'waitUntil') {
+        return function waitUntil(promise: Promise<unknown>) {
+          waitUntilPromises.push(promise.catch(err => console.error(err)));
+        };
+      }
       if (prop in extraProps) {
         return Reflect.get(extraProps, prop, receiver);
       }
@@ -468,6 +474,9 @@ export function isolateObject<TIsolatedObject extends object>(
       return Reflect.set(extraProps, prop, value, receiver);
     },
     has(originalCtx, prop) {
+      if (waitUntilPromises != null && prop === 'waitUntil') {
+        return true;
+      }
       if (deletedProps.has(prop)) {
         return false;
       }
@@ -490,9 +499,13 @@ export function isolateObject<TIsolatedObject extends object>(
       const extraKeys = Reflect.ownKeys(extraProps);
       const originalKeys = Reflect.ownKeys(originalCtx);
       const deletedKeys = Array.from(deletedProps);
-      return Array.from(
-        new Set(extraKeys.concat(originalKeys.filter(keys => !deletedKeys.includes(keys)))),
+      const allKeys = new Set(
+        extraKeys.concat(originalKeys.filter(keys => !deletedKeys.includes(keys))),
       );
+      if (waitUntilPromises != null) {
+        allKeys.add('waitUntil');
+      }
+      return Array.from(allKeys);
     },
     getOwnPropertyDescriptor(originalCtx, prop) {
       if (prop in extraProps) {
diff --git a/packages/server/test/server-context.spec.ts b/packages/server/test/server-context.spec.ts
index e3efebc974d..90acf8d2346 100644
--- a/packages/server/test/server-context.spec.ts
+++ b/packages/server/test/server-context.spec.ts
@@ -1,3 +1,5 @@
+import { Request } from '@whatwg-node/fetch';
+import { Response } from '@whatwg-node/server';
 import { createServerAdapter } from '../src/createServerAdapter';
 
 describe('Server Context', () => {
@@ -20,4 +22,13 @@ describe('Server Context', () => {
     expect(seenCtx.has(exampleStaticCtx)).toBe(false);
     expect(exampleStaticCtx.foo).toBe('bar');
   });
+  it('filters empty ctx', async () => {
+    const adapter = createServerAdapter<any>(function handler(_req, ctx) {
+      return Response.json(ctx);
+    });
+    const ctxParts: any[] = [undefined, undefined, { foo: 'bar' }, undefined, { bar: 'baz' }];
+    const res = await adapter(new Request('https://example.com'), ...ctxParts);
+    expect(res.status).toBe(200);
+    expect(await res.json()).toEqual({ foo: 'bar', bar: 'baz' });
+  });
 });