Flutter ios build fails. simulator builds also fail - flutter

Question

I've been working on an app for months now and using Flutter, but whenever I upgrade Flutter, it is a huge pain because I have to wrestle to try to get it to build again. Usually manually cleaning up CocoaPods and pubspec.yaml is enough, but this time it hasn't.
I've upgraded my Flutter version to 1.14.6 from 1.10.7, nuked my pods and pubspec.yaml, nuked my installation of Flutter, my repository, and nothing worked.
Another weird thing about it is that I have the build running just fine with the same versions of flutter, dart, cocoapods, and ruby on the same branch on a different machine. Is there something cached somewhere that I am not cleaning up properly? When I try to build, it says it fails with errors, but unfortunately the log output doesn't actually show any errors, and only shows warnings. Here is a part of my log output:
8 warnings generated.
/Users/hallo/Documents/dev/flutter/.pub-cache/hosted/pub.dartlang.org/google_sign_in-4.1.1/ios/Classes/FLTGoogleSignInPlugin.m:138:13: warning: unused variable 'sourceApplication' [-Wunused-variable]
NSString *sourceApplication = options[UIApplicationOpenURLOptionsSourceApplicationKey];
^
/Users/hallo/Documents/dev/flutter/.pub-cache/hosted/pub.dartlang.org/google_sign_in-4.1.1/ios/Classes/FLTGoogleSignInPlugin.m:138:41: warning: 'UIApplicationOpenURLOptionsSourceApplicationKey' is only available on iOS 9.0 or newer [-Wunguarded-availability]
NSString *sourceApplication = options[UIApplicationOpenURLOptionsSourceApplicationKey];
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In module 'UIKit' imported from /Users/hallo/Documents/HalloMonoRepo/hallo/ios/Pods/Target Support Files/google_sign_in/google_sign_in-prefix.pch:2:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator13.0.sdk/System/Library/Frameworks/UIKit.framework/Headers/UIApplication.h:514:51: note: 'UIApplicationOpenURLOptionsSourceApplicationKey' has been marked as being introduced in iOS 9.0 here, but the deployment target is iOS 8.0.0
UIKIT_EXTERN UIApplicationOpenURLOptionsKey const UIApplicationOpenURLOptionsSourceApplicationKey NS_SWIFT_NAME(sourceApplication) API_AVAILABLE(ios(9.0)); // value is an NSString containing the bundle ID of the originating application; non-nil if the originating application and this application share the same team identifier
^
/Users/hallo/Documents/dev/flutter/.pub-cache/hosted/pub.dartlang.org/google_sign_in-4.1.1/ios/Classes/FLTGoogleSignInPlugin.m:138:41: note: enclose 'UIApplicationOpenURLOptionsSourceApplicationKey' in an #available check to silence this warning
NSString *sourceApplication = options[UIApplicationOpenURLOptionsSourceApplicationKey];
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Could not build the application for the simulator.
Error launching application on iPhone 8.
Any help would be much appreciated as I have exhausted my ideas on what could be causing this error.
Pluto:hallo hallo$ flutter doctor -v
[✓] Flutter (Channel beta, v1.14.6, on Mac OS X 10.14.6 18G3020, locale en-US)
• Flutter version 1.14.6 at /Users/hallo/Documents/dev/flutter
• Framework revision fabeb2a16f (3 weeks ago), 2020-01-28 07:56:51 -0800
• Engine revision c4229bfbba
• Dart version 2.8.0 (build 2.8.0-dev.5.0 fc3af737c7)
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
• Android SDK at /Users/hallo/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-29, build-tools 29.0.2
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 11.0)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 11.0, Build version 11A420a
• CocoaPods version 1.8.4
[✓] Android Studio (version 3.4)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 39.0.1
• Dart plugin version 183.6270
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)
[✓] VS Code (version 1.42.1)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.8.1
[✓] Connected device (1 available)
• iPhone 8 • C40DD8DB-5860-4B94-8D20-372074B6E7BC • ios • com.apple.CoreSimulator.SimRuntime.iOS-13-0 (simulator)
• No issues found!`

Answer 1

Are you running on Android Studio? VS Code? Could you post your flutter doctor -v?
Other than that, all those errors comes from google_sign_in. Would recommend the following:
Remove google_sign_in (and comment any screens using this dependency)
Make sure you're following all the correct changes inside your iOS Folder
Use a different library. google_sign_in may not be up to date with all the latest Flutter changes.
If your code runs without that library, it clearly shows an error with the latest upgrade changes.

Answer 2

I fixed the issue by changing a variety of things. When I did the flutter upgrade, it changed my project.pbxproj file by adding this line
shellScript = "# Type a script or drag a script file from your workspace to insert its path.\n\"${PODS_ROOT}/Fabric/run\"\n";
which caused a lot of errors. I deleted this line, changed the build system in Xcode to default (it was legacy), and then in the embed frameworks in Xcode, I removed Flutter.framework.

Answer 3

Just run flutter clean on your project, it did the trick for me.