diff --git a/.changeset/spotty-pandas-wait.md b/.changeset/spotty-pandas-wait.md
new file mode 100644
index 000000000000..975e838fa90c
--- /dev/null
+++ b/.changeset/spotty-pandas-wait.md
@@ -0,0 +1,6 @@
+---
+'@sveltejs/adapter-netlify': patch
+'@sveltejs/adapter-vercel': patch
+---
+
+fix: await `init` on every request to prevent race condition
diff --git a/packages/adapter-netlify/src/edge.js b/packages/adapter-netlify/src/edge.js
index f0d9944741ca..348549015331 100644
--- a/packages/adapter-netlify/src/edge.js
+++ b/packages/adapter-netlify/src/edge.js
@@ -31,9 +31,11 @@ const initialized = server.init({
 export default async function handler(request, context) {
 	if (!origin) {
 		origin = new URL(request.url).origin;
-		await initialized;
 	}
 
+	// always await initialization to prevent race condition with concurrent requests
+	await initialized;
+
 	return server.respond(request, {
 		platform: { context },
 		getClientAddress() {
diff --git a/packages/adapter-vercel/files/edge.js b/packages/adapter-vercel/files/edge.js
index f87bb6e64a98..70707543b2ce 100644
--- a/packages/adapter-vercel/files/edge.js
+++ b/packages/adapter-vercel/files/edge.js
@@ -54,9 +54,11 @@ const initialized = server.init({
 export default async (request, context) => {
 	if (!origin) {
 		origin = new URL(request.url).origin;
-		await initialized;
 	}
 
+	// always await initialization to prevent race condition with concurrent requests
+	await initialized;
+
 	return server.respond(request, {
 		getClientAddress() {
 			return /** @type {string} */ (request.headers.get('x-forwarded-for'));