How to fix 'Flutter/Flutter.h' file not found

Last week when I last worked on this it was building ok. Stopped working on this while adding new feature to an other app, week-end break I come back and both app do not compile any more. one is complaing that it as a socket exeception, and the other one as the below problem.

Could not build the precompiled application for the device.
Lexical or Preprocessor Issue (Xcode): 'Flutter/Flutter.h' file not found
/Users/user/.pub-cache/hosted/pub.dev/flutter_blue_plus-1.32.7/ios/Classes/FlutterBluePlusPlugin.h:7:8

Lexical or Preprocessor Issue (Xcode): 'Flutter/Flutter.h' file not found
/Users/user/.pub-cache/hosted/pub.dev/package_info_plus-8.0.0/ios/Classes/FPPPackageInfoPlusPlugin.h:4:8

Uncategorized (Xcode): Command SwiftEmitModule failed with a nonzero exit code


Error launching application on AR18 iPhone.

I tried the usual stuff DT_TOOLCHAIN_DIR cannot be used to evaluate LIBRARY_SEARCH_PATHS, use TOOLCHAIN_DIR instead in xcode 15 I even asked GPT for some help. Nothing as worked.

So to make a quick list. -fully remove the cocoa pods, re-istalled them and update the repo.

delete the ios folder to re-generate it.. a few times (just in case).
cleaned, and cleaned flutter and ios projects.
deleted xcode cache files.
change my pod file (see below)

Still not able to get the app to build.

Podfile

# Uncomment this line to define a global platform for your project
platform :ios, '13.0'

# CocoaPods analytics sends network stats synchronously affecting flutter build latency.
ENV['COCOAPODS_DISABLE_STATS'] = 'true'

project 'Runner', {
  'Debug' => :debug,
  'Profile' => :release,
  'Release' => :release,
}

def flutter_root
  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
  unless File.exist?(generated_xcode_build_settings_path)
    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"
  end

  File.foreach(generated_xcode_build_settings_path) do |line|
    matches = line.match(/FLUTTER_ROOT\=(.*)/)
    return matches[1].strip if matches
  end
  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"
end

require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)

flutter_ios_podfile_setup

target 'Runner' do
  use_frameworks!
  use_modular_headers!

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
  target 'RunnerTests' do
    inherit! :search_paths
  end
end

post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['ENABLE_BITCODE'] = 'NO'
      config.build_settings['CLANG_ENABLE_MODULES'] = 'YES'
      config.build_settings['SWIFT_VERSION'] = '5.0'
    end
  end
end

-fully remove the cocoa pods, re-istalled them and update the repo.

delete the ios folder to re-generate it.. a few times (just in case).
cleaned, and cleaned flutter and ios projects.
deleted xcode cache files.
change my pod file

Solution

Make sure all the plugins are up-to-date and compatible with the flutter version you are using currently.