Flutter errorFlutter: “SocketException: Failed host lookup: 'api.example.com' (OS Error: No address associated with hostname, errno = 7)”

Why the lookup failed, and the fix

1. 01

   No INTERNET permission in the release manifest

   “Android apps must declare their use of the internet in the Android manifest” Flutter, Networking

   A new Flutter project adds the INTERNET permission only to the debug and profile manifests, so a release build or a Play Store install has no network. Add it to the main manifest, outside the application tag, then stop the app and run it again: hot reload and hot restart don’t pick up manifest changes.

   <!-- android/app/src/main/AndroidManifest.xml -->
   <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.INTERNET" />
     <application ...>

2. 02

   A macOS app without the network entitlement

   “macOS apps must allow network access in the relevant *.entitlements files.” Flutter, Networking

   macOS apps are sandboxed. Add the network client key to macos/Runner/DebugProfile.entitlements and Release.entitlements; the debug file alone makes it fail only in release. Rebuild the app after the change.

   <key>com.apple.security.network.client</key>
   <true/>

3. 03

   The emulator or device has no working DNS

   An Android emulator that lost its network after the computer changed Wi-Fi or VPN can’t resolve any name. Open a website in the emulator’s browser. If it fails too, cold boot the emulator, start it with a public DNS server (emulator -avd NAME -dns-server 8.8.8.8), or wipe its data; on a phone, switch networks or turn off a VPN or Private DNS setting that blocks the host.

4. 04

   A wrong host name, or an app that assumes it is online

   “Exception thrown when a socket operation fails.” Dart, SocketException class

   A typo in the host name, or a base URL built from the wrong environment variable, fails the lookup. (An empty URL or http://localhost gives a different error; see the FAQ.) Log the full URL before the request. Real users go offline too, so catch SocketException and show a retry message instead of a crash.

   try {
     final res = await http.get(Uri.parse('$baseUrl/orders'));
   } on SocketException catch (e) {
     // e.message: Failed host lookup
     showOfflineBanner();
   }

Checked against the vendor’s docs on November 8, 2026: Flutter: Networking (Android permission, macOS entitlement); Android Developers: Connect to the network (INTERNET permission); Dart API: SocketException class.

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