diff --git a/.changeset/wise-ads-roll.md b/.changeset/wise-ads-roll.md
new file mode 100644
index 00000000000..20679dddba8
--- /dev/null
+++ b/.changeset/wise-ads-roll.md
@@ -0,0 +1,5 @@
+---
+'@whatwg-node/server': patch
+---
+
+Fix descriptor issue when .fetch is used with dummy context
diff --git a/packages/server/src/utils.ts b/packages/server/src/utils.ts
index 2fe12579270..240bf72e156 100644
--- a/packages/server/src/utils.ts
+++ b/packages/server/src/utils.ts
@@ -409,7 +409,10 @@ export function completeAssign(...args: any[]) {
     // modified Object.keys to Object.getOwnPropertyNames
     // because Object.keys only returns enumerable properties
     const descriptors: any = Object.getOwnPropertyNames(source).reduce((descriptors: any, key) => {
-      descriptors[key] = Object.getOwnPropertyDescriptor(source, key);
+      const descriptor = Object.getOwnPropertyDescriptor(source, key);
+      if (descriptor) {
+        descriptors[key] = Object.getOwnPropertyDescriptor(source, key);
+      }
       return descriptors;
     }, {});