title: Why does Flutter compiler tell me that my app doesn't exist?
body: <p>I'm making an app with Flutter and I need to fetch some data from a Firestore database. I followed the steps to include it in the iOS Xcode project, but I get an error after Xcode build. I am not even using Firebase yet in the app.</p>
  
  <p>I found this answer: <a href="https://stackoverflow.com/questions/42197729/app-getting-crash-when-click-on-googlesignin-button">App getting crash when click on GoogleSignIn button</a></p>
  
  <p>But it does not correspond to my problem.</p>
  
  <p>This is the AppDelegate.m (no error reported by Xcode): </p>
  
  <pre><code>#include "AppDelegate.h"
  #include "GeneratedPluginRegistrant.h"
  #import "GoogleMaps/GoogleMaps.h"
  
  @import Firebase;
  
  @implementation AppDelegate
  
  - (BOOL)application:(UIApplication *)application
      didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
      [GMSServices provideAPIKey:@"XXXX"];
    [GeneratedPluginRegistrant registerWithRegistry:self];
      [FIRApp configure];
    // Override point for customization after application launch.
    return [super application:application didFinishLaunchingWithOptions:launchOptions];
  }
  
  @end
  </code></pre>
  
  <p>This is the error I get:</p>
  
  <pre><code>Launching lib/main.dart on iPhone 8 in debug mode...
  Running Xcode build...
  Xcode build done.                                            7,8s
  Configuring the default Firebase app...
  6.0.0 - [Firebase/Core][I-COR000004] App with name __FIRAPP_DEFAULT does not exist.
  6.0.0 - [Firebase/Analytics][I-ACS023007] Analytics v.60000000 started
  6.0.0 - [Firebase/Analytics][I-ACS023008] To enable debug logging set the following application argument: -FIRAnalyticsDebugEnabled (see XXXX)
  Configured the default Firebase app __FIRAPP_DEFAULT.
  6.0.0 - [Firebase/Core][I-COR000027] The library name (flutter-firebase_core) or version number (0.4.0+1) contain invalid characters. Only alphanumeric, dash, underscore and period characters are allowed.
  *** First throw call stack:
  (
      0   CoreFoundation                      0x000000010f5d26fb __exceptionPreprocess + 331
      1   libobjc.A.dylib                     0x000000010eb76ac5 objc_exception_throw + 48
      2   CoreFoundation                      0x000000010f5d2555 +[NSException raise:format:] + 197
      3   Runner                              0x00000001076ca6b6 +[FIRApp configureWithName:options:] + 326
      4   Runner                              0x00000001076ca54f +[FIRApp configureWithOptions:] + 143
      5   Runner                              0x00000001076ca47f +[FIRApp configure] + 607
      6   Runner                              0x000000010757e61c -[AppDelegate application:didFinishLaunchingWithOptions:] + 156
      7   UIKitCore                           0x0000000119a83311 -[UIApplication _handleDelegateCallbacksWithOptions:isSuspended:restoreState:] + 280
      8   UIKitCore                           0&lt;…&gt;
  Error connecting to the service protocol: HttpException: Connection closed before full header was received, uri = http://127.0.0.1:54573/It0MI4dOUXE=/ws
  </code></pre>
  
  <p>And this is Flutter doctor output:</p>
  
  <pre><code>[✓] Flutter (Channel stable, v1.5.4-hotfix.2, on Mac OS X 10.14.4 18E226, locale fr-FR)
      • Flutter version 1.5.4-hotfix.2 at /Users/mickaeldebalme/SDK/Flutter/flutter
      • Framework revision 7a4c33425d (3 weeks ago), 2019-04-29 11:05:24 -0700
      • Engine revision 52c7a1e849
      • Dart version 2.3.0 (build 2.3.0-dev.0.5 a1668566e5)
  
  
  [✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
      • Android SDK at /Users/mickaeldebalme/Library/Android/sdk
      • Android NDK location not configured (optional; useful for native profiling support)
      • Platform android-28, build-tools 28.0.3
      • Java binary at: /Users/mickaeldebalme/Library/Application
        Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/182.5314842/Android
        Studio.app/Contents/jre/jdk/Contents/Home/bin/java
      • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
      • All Android licenses accepted.
  
  [✓] iOS toolchain - develop for iOS devices (Xcode 10.2.1)
      • Xcode at /Applications/Xcode.app/Contents/Developer
      • Xcode 10.2.1, Build version 10E1001
      • ios-deploy 1.9.4
      • CocoaPods version 1.6.1
  
  [✓] Android Studio (version 3.3)
      • Android Studio at /Users/mickaeldebalme/Library/Application
        Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/182.5314842/Android Studio.app/Contents
      • Flutter plugin version 34.0.1
      • Dart plugin version 182.5215
      • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
  
  [✓] Connected device (1 available)
      • iPhone 8 • B6399A10-1F2D-44C3-8B0D-6AD086AD0F55 • ios •
        com.apple.CoreSimulator.SimRuntime.iOS-12-2 (simulator)
  
  • No issues found!
  </code></pre>
  
  <p><strong>EDIT</strong>
  After creating a clean project, the error was still there.
  So I did the following:</p>
  
  <ul>
  <li>Upgrading all my plugins to the latest version</li>
  <li>Migrating to Android X</li>
  <li>Moving the <code>[FIRApp configure];</code> above the rest of the Objective-C instructions in the AppDelegate.m (yes !)</li>
  </ul>