Build error header "has been modified since the module file" pcm "was built: size changed" #190449

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1. jmagman

   added

   platform-iosiOS applications specificallyiOS applications specifically

   toolAffects the "flutter" command-line tool. See also t: labels.Affects the "flutter" command-line tool. See also t: labels.

   platform-macosBuilding on or for macOS specificallyBuilding on or for macOS specifically

   t: xcode"xcodebuild" on iOS and general Xcode project management"xcodebuild" on iOS and general Xcode project management

   team-iosOwned by iOS platform teamOwned by iOS platform team

   on Aug 3, 2026
2. jmagman

   changed the title [-]Build error header "has been modified since the module file" FlutterMacOS-EB2I1X8OEY51SORFFEHAHR5XK.pcm "was built: size changed"[/-] [+]Build error header "has been modified since the module file" pcm "was built: size changed"[/+] on Aug 3, 2026
3. vashworth commented on Aug 3, 2026

   

   vashworth

   on Aug 3, 2026

   Contributor

   More actions

   iOS already handles this:

   flutter/packages/flutter_tools/lib/src/ios/mac.dart

   Lines 310 to 329 in 5a2a94a

   	// Check the public headers before checking Xcode version so headers fingerprinter is created
   	// regardless of Xcode version.
   	final bool headersChanged = publicHeadersChanged(
   	environmentType: environmentType,
   	mode: buildInfo.mode,
   	buildDirectory: buildDirectoryPath,
   	artifacts: globals.artifacts,
   	fileSystem: globals.fs,
   	logger: globals.logger,
   	);
   	final Version? xcodeVersion = globals.xcode?.currentVersion;
   	if (headersChanged &&
   	incrementalBuild &&
   	(xcodeVersion != null && xcodeVersion >= Version(26, 0, 0))) {
   	// Xcode 26 changed the way headers are pre-compiled and will throw an error if the headers
   	// have changed since the last time they were compiled. To avoid this error, clean before
   	// building if headers have changed.
   	targetBuildDir.deleteSync(recursive: true);
   	buildCommands.addAll(<String>['clean', 'build']);
   	}

   flutter/packages/flutter_tools/lib/src/ios/mac.dart

   Lines 1096 to 1101 in 5a2a94a

   	} else if (message.toLowerCase().contains('has been modified since')) {
   	return _XCResultIssueHandlingResult(
   	requiresProvisioningProfile: false,
   	hasProvisioningProfileIssue: false,
   	modifiedPrecompiledSource: true,
   	);

   But macOS doesn't since we don't have unified tooling: #144397
4. vashworth

   added

   team-macosOwned by the macOS platform teamOwned by the macOS platform team

   P2Important issues not at the top of the work listImportant issues not at the top of the work list

   triaged-macosTriaged by the macOS platform teamTriaged by the macOS platform team

   and removed

   team-iosOwned by iOS platform teamOwned by iOS platform team

   on Aug 6, 2026