[tool_crash] Unhandled ProcessPackageException (OS Error 206: The filename or extension is too long) in _DefaultPub._preloadPubCache #194570

Summary

flutter pub get crashes on Windows with an unhandled ProcessPackageException (ProcessException: The filename or extension is too long, OS error code 206 / ERROR_FILENAME_EXCED_RANGE) in _DefaultPub._preloadPubCache (package:flutter_tools/src/dart/pub.dart:645) / ErrorHandlingProcessManager.runSync (package:flutter_tools/src/base/error_handling_io.dart:1310).

Crash Telemetry (Flutter stable/3.47.7)

• Signature: ProcessPackageException at LocalProcessManager.runSync at package:process/src/interface/local_process_manager.dart-313da74f
• Rank: fix syntax error #10 Top Crasher in 3.47.7
• Total Occurrences: 19 (3.7% of Top 10, 1.9% of all 3.47.7 crashes, ~2.5 crashes/day)
• Platform Distribution: Windows: 19 (100.0%)
• Sample Command: flutter pub get
• Error:

ProcessException: The filename or extension is too long (at ../../runtime/bin/process_win.cc:579) | Command: C:\Users\User\AppData\Local\Temp\claude\d--Dotlinker-Laravel-New-Set...

Stack Trace

#0      LocalProcessManager.runSync (package:process/src/interface/local_process_manager.dart:118)
#1      ErrorHandlingProcessManager.runSync.<anonymous closure> (package:flutter_tools/src/base/error_handling_io.dart:1310)
#2      _runSync (package:flutter_tools/src/base/error_handling_io.dart:1118)
#3      ErrorHandlingProcessManager.runSync (package:flutter_tools/src/base/error_handling_io.dart:1308)
#4      _DefaultPub._preloadPubCache (package:flutter_tools/src/dart/pub.dart:645)
#5      _DefaultPub._getPubCacheIfAvailable (package:flutter_tools/src/dart/pub.dart:624)
#6      _DefaultPub._createPubEnvironment (package:flutter_tools/src/dart/pub.dart:664)
#7      _DefaultPub._runWithStdioInherited (package:flutter_tools/src/dart/pub.dart:379)

Root Cause

1. In _DefaultPub._preloadPubCache (package:flutter_tools/src/dart/pub.dart), flutter_tools passes all .tar.gz archive paths in $FLUTTER_ROOT/.pub-preload-cache to a single _processManager.runSync(<String>[..._pubCommand, 'cache', 'preload', ...cacheFiles]) invocation. When the Flutter SDK or current working directory is located in a deep Windows path (or the concatenated .tar.gz paths exceed Windows CreateProcessW / MAX_PATH limits in runtime/bin/process_win.cc), Windows fails with error code 206 (ERROR_FILENAME_EXCED_RANGE: The filename or extension is too long).
2. In _handleWindowsException (package:flutter_tools/src/base/error_handling_io.dart:1467-1522), error code 206 is not listed in the switch (errorCode) statement, so _onProcessException returns without throwing a ToolExit and _runSync rethrows the raw ProcessPackageException.

Recommendation

1. Add const kFilenameExcedRange = 206; (ERROR_FILENAME_EXCED_RANGE) to _handleWindowsException in package:flutter_tools/src/base/error_handling_io.dart so process/filesystem calls failing with error code 206 exit cleanly with a ToolExit instructing the user to move the project/SDK to a shorter path or enable Windows Long Paths.
2. In _DefaultPub._preloadPubCache (package:flutter_tools/src/dart/pub.dart), batch cacheFiles (or run with workingDirectory: preloadCacheDir.path using relative archive filenames) so dart pub cache preload does not exceed Windows command-line / path length limits.