Flutter iOS: “A number of instructions produce .app” error on Xcode 16.4. Even legacy construct system fails

I preserve getting these “A number of instructions produce” errors when constructing my Flutter iOS app. This began after updating to macOS 15.6 and Xcode 16.4.

Error:

Error (Xcode): A number of instructions produce ‘/Customers/tafseerapp/Tafseer/construct/ios/Debug-iphonesimulator/.app’
word: Goal ‘Runner’ (challenge ‘Runner’) has create listing command with output
word: Goal ‘Runner’ (challenge ‘Runner’) has hyperlink command with output

Setting:

macOS: 15.6 (24G84)

Xcode: 16.4 (Construct model 16F6)

Flutter: 3.32.8 (newest secure). Additionally tried beta channel

CocoaPods: 1.16.2

Account: Secondary person account (not admin)

Present Podfile:

platform :ios, '13.0'
set up! 'cocoapods', :disable_input_output_paths => true
set up! 'cocoapods', :disable_input_output_paths => true
set up! 'cocoapods', :disable_input_output_paths => true
set up! 'cocoapods', :disable_input_output_paths => true

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

challenge 'Runner', {
  'Debug' => :debug,
  'Profile' => :launch,
  'Launch' => :launch,
}

def flutter_root
  generated_xcode_build_settings_path = File.expand_path(File.be part of('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
  until File.exist?(generated_xcode_build_settings_path)
    elevate "#{generated_xcode_build_settings_path} should exist. Should you're working pod set up manually, ensure flutter pub get is executed first"
  finish

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

require File.expand_path(File.be part of('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)

flutter_ios_podfile_setup

goal 'Runner' do
  use_frameworks!

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
  goal 'RunnerTests' do
    inherit! :search_paths
  finish
finish

post_install do |installer|
  installer.pods_project.targets.every do |goal|
    flutter_additional_ios_build_settings(goal)
  finish
finish

What I’ve Tried:

Legacy Construct System
Firebase SDK downgrade (11.8.0 → 10.x variations);
Flutter beta channel
set up! ‘cocoapods’, :disable_input_output_paths => true
Full pod deintegrate/reinstall
Checked Copy Bundle Sources (no Data.plist duplicates)
flutter create . to regenerate iOS challenge;
Permissions repair: sudo chown -R $USER ~/Library/Developer/Xcode/DerivedData
Created minimal Flutter app (builds efficiently with out Firebase)

Key findings:

Minimal Flutter app with out Firebase builds fantastic
Identical error persists even with legacy construct system
Verbose output reveals gRPC-related warnings (Firebase dependencies)
Construct phases look regular (no apparent duplicates)

What else might trigger “A number of instructions produce” when even legacy construct system fails? This appears to be particular to Firebase + Xcode 16.4 + macOS 15.6 mixture.