Flutter – path_provider_foundation.modulemap not found

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Summary

A developer encountered a blocking build failure in a Flutter iOS project after updating Xcode to version 26.0.1. The build logs reported fatal errors regarding missing module map files for path_provider_foundation. Standard remediation steps, such as cleaning the project, reinstalling CocoaPods, and deleting derived data, failed to resolve the issue. The root cause was identified as an incompatible dependency version between the Flutter framework, the specific Dart package, and the updated Xcode toolchain, combined with a stale build cache that persisted across standard clean operations. The resolution required manual inspection of Podfile.lock and forced version resolution to ensure path_provider_foundation was upgraded to a version compatible with Xcode 26.

Root Cause

The primary cause of the failure was a mismatch in the expected file structure for Swift modules introduced by the Xcode update, specifically regarding Swift Interface Generation.

  • Incompatible Package Version: The version of path_provider_foundation locked in Podfile.lock likely relied on older module mapping conventions that are incompatible with the stricter module resolution logic in Xcode 26.0.1.
  • Persistent Derived Data Corruption: The user attempted to delete derived data, but the modulemap file is often generated during the pod install or flutter build ios phase. If the Podfile.lock pins an old version, regenerating the project simply recreates the broken file structure.
  • Missing Explicit Version Pinning: The Podfile did not explicitly constrain the version of path_provider_foundation, allowing pub get to resolve to a version that was technically valid for the Flutter version but semantically incompatible with the new Xcode build engine.

Why This Happens in Real Systems

In complex build systems like Xcode, ABI stability and module interfaces are strictly enforced.

  • Toolchain Drift: When Xcode updates, it often changes how it parses .modulemap files. If a Flutter plugin hasn’t been updated to emit the new format, the compiler cannot locate the module definition, leading to the “module map file not found” error.
  • Flaky Cache Invalidation: Standard clean commands (flutter clean, deleting DerivedData) often do not clear the Podfile.lock or the cached pod artifacts. If the build system assumes these artifacts are valid based on timestamps, it skips re-generation, leaving the developer in a state where the files on disk are valid for an old toolchain but invalid for the new one.

Real-World Impact

  • Zero-Velocity Development: The team is completely blocked from building or testing the iOS application.
  • False-Positive Debugging: The “53 errors” cascading from one missing module map often point to standard libraries (like SwiftUI or Foundation), misleading developers into thinking their environment is fundamentally broken rather than a single dependency being out of date.
  • CI/CD Pipeline Failure: This issue prevents deployment pipelines from passing if they use the updated Xcode image, causing release delays.

Example or Code

The user’s Podfile included use_modular_headers!, which forces Swift modules to be built with modular interfaces. This interacts strictly with the path_provider_foundation dependency.

To fix this, the dependency must be explicitly upgraded to a version that supports the new Xcode changes (usually 0.2.3 or higher).

# In your Podfile, you can force a specific version or allow flutter to upgrade it
# by modifying the pubspec.yaml or running this specific pod update command.

# However, since this is a transitive dependency, the fix usually happens in pubspec.yaml
# or by forcing the pod update here:

target 'Runner' do
  use_modular_headers!

  # Explicitly update the problematic pod before installing all others
  pod 'path_provider_foundation', :git => 'https://github.com/flutter/packages', :branch => 'main'

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

How Senior Engineers Fix It

Senior engineers approach this by isolating the dependency graph rather than randomly cleaning files.

  1. Pin and Prune: They check Podfile.lock to identify the exact version of path_provider_foundation causing the issue. They then modify pubspec.yaml to restrict the dependency to a known working version (or explicitly update it to the latest stable).
  2. Force Lockfile Refresh: Instead of just flutter clean, they run flutter pub deps to verify the tree and then delete Podfile.lock and ios/Pods/ to force a complete recalculation of the dependency graph.
  3. Analyze Build Logs: They look at the full build log (often via Xcode -> Report -> Show logs) to see the exact compiler flag that failed, confirming it is a module map issue rather than a missing file issue.
  4. Bypass Modular Headers (If safe): If the specific plugin doesn’t need to be modular, they might remove use_modular_headers! or override it specifically for the failing pod to stop the compiler from looking for a .modulemap file that doesn’t exist.

Why Juniors Miss It

  • Reliance on “Magic” Commands: Juniors often memorize a list of “fix-it” commands (flutter clean, pod deintegrate) without understanding what those commands modify. They don’t realize that Podfile.lock preserves the broken version number.
  • Misinterpreting Error Scope: Seeing 53 errors makes a developer think the whole project is broken. They miss the pattern that all errors point to the same missing file, indicating a single dependency root cause.
  • Blindly Following Old Tutorials: They follow guides that may be outdated for Xcode 26, failing to realize that the issue is a version incompatibility, not a configuration error.