Flutter app doesn't start since updating flutter

Question

Please help me! The app was close to be finished and since I did run flutter upgrade to solve a bug I had to run: flutter clean flutter channel master flutter upgrade flutter run

and now its not starting anymore and the following code shows up..

Launching lib/main.dart on iPhone 12 Pro Max in debug mode...
Running Xcode build...
Xcode build done.                                           42,0s
Failed to build iOS app
Error output from Xcode build:
↳
    ** BUILD FAILED **


Xcode's output:
↳
    In file included from /Users/patrickmeyer/Developer/flutter/.pub-cache/hosted/pub.dartlang.org/shared_preferences-0.5.12+4/ios/Classes/FLTSharedPreferencesPlugin.m:5:
    /Users/patrickmeyer/Developer/flutter/.pub-cache/hosted/pub.dartlang.org/shared_preferences-0.5.12+4/ios/Classes/FLTSharedPreferencesPlugin.h:5:9: fatal error: 'Flutter/Flutter.h' file not found
    #import <Flutter/Flutter.h>
            ^~~~~~~~~~~~~~~~~~~
    1 error generated.
    note: Using new build system
    note: Building targets in parallel
    note: Planning build
    note: Constructing build description
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'share' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'GoogleDataTransport' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'shared_preferences' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'Firebase' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'GoogleUtilities' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'GoogleAppMeasurement' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'firebase_core' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'FirebaseCore' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'FirebaseCoreDiagnostics' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'firebase_admob' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 4.3, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'nanopb' from project 'Pods')
    warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0, but the range of supported deployment target versions is 9.0 to 14.3.99. (in target 'Flutter' from project 'Pods')

Could not build the application for the simulator.
Error launching application on iPhone 12 Pro Max.

Flutter doctor seems to look fine...

[✓] Flutter (Channel stable, 1.22.5, on Mac OS X 10.15.7 19H114 darwin-x64, locale de-DE) • Flutter version 1.22.5 at /Users/patrickmeyer/Developer/flutter • Framework revision 7891006299 (13 days ago), 2020-12-10 11:54:40 -0800 • Engine revision ae90085a84 • Dart version 2.10.4

[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3) • Android SDK at /Users/patrickmeyer/Library/Android/sdk • Platform android-29, build-tools 29.0.3 • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495) • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.3) • Xcode at /Applications/Xcode.app/Contents/Developer • Xcode 12.3, Build version 12C33 • CocoaPods version 1.10.0

[✓] Android Studio (version 4.1) • Android Studio at /Applications/Android Studio.app/Contents • Flutter plugin installed • Dart plugin version 201.9306 • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] Connected device (1 available) • iPhone 12 Pro Max (mobile) • 11ACA273-A0C3-405D-993A-A9AF9057887C • ios • com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)

• No issues found!

Solution

run pod update in your pod file