diff --git a/.changeset/three-pumas-cough.md b/.changeset/three-pumas-cough.md
new file mode 100644
index 0000000..f7ffb5c
--- /dev/null
+++ b/.changeset/three-pumas-cough.md
@@ -0,0 +1,5 @@
+---
+'@hono/vite-dev-server': patch
+---
+
+fix(dev-server): Add null check and error handling for proxy disposal in cloudflareAdapter
diff --git a/packages/dev-server/src/adapter/cloudflare.ts b/packages/dev-server/src/adapter/cloudflare.ts
index 0e5872f..02f0ce3 100644
--- a/packages/dev-server/src/adapter/cloudflare.ts
+++ b/packages/dev-server/src/adapter/cloudflare.ts
@@ -8,7 +8,7 @@ type CloudflareAdapterOptions = {
   proxy: Parameters<typeof getPlatformProxy>[0]
 }
 
-let proxy: Awaited<ReturnType<typeof getPlatformProxy<Env>>>
+let proxy: Awaited<ReturnType<typeof getPlatformProxy<Env>>> | undefined = undefined
 
 export const cloudflareAdapter: (options?: CloudflareAdapterOptions) => Promise<Adapter> = async (
   options
@@ -16,7 +16,6 @@ export const cloudflareAdapter: (options?: CloudflareAdapterOptions) => Promise<
   proxy ??= await getPlatformProxy(options?.proxy)
   // Cache API provided by `getPlatformProxy` currently do nothing.
   Object.assign(globalThis, { caches: proxy.caches })
-
   if (typeof globalThis.navigator === 'undefined') {
     // @ts-expect-error not typed well
     globalThis.navigator = {
@@ -31,7 +30,10 @@ export const cloudflareAdapter: (options?: CloudflareAdapterOptions) => Promise<
 
   Object.defineProperty(Request.prototype, 'cf', {
     get: function () {
-      return proxy.cf
+      if (proxy !== undefined) {
+        return proxy.cf
+      }
+      throw new Error('Proxy is not initialized')
     },
     configurable: true,
     enumerable: true,
@@ -41,12 +43,16 @@ export const cloudflareAdapter: (options?: CloudflareAdapterOptions) => Promise<
     env: proxy.env,
     executionContext: proxy.ctx,
     onServerClose: async () => {
-      try {
-        await proxy.dispose()
-      } catch {
-        /**
-         * It throws an error if server is not running.
-         */
+      if (proxy !== undefined) {
+        try {
+          await proxy.dispose()
+        } catch (error) {
+          /**
+           * It throws an error if server is not running.
+           */
+        } finally {
+          proxy = undefined
+        }
       }
     },
   }