C:\src\flutter\flutter\packages\flutter_tools [roll-engine-20180322 ≡]> ..\..\bin\cache\dart-sdk\bin\pub upgrade --verbosity=normal --no-packages-dir
Resolving dependencies...
The method 'read' was called on null.
Receiver: null
Tried calling: read(Instance of '_SimpleUri', headers: Instance of '_ImmutableMap')
package:pub/src/source/hosted.dart 339                                                         BoundHostedSource._throwFriendlyError
package:pub/src/source/hosted.dart 141                                                         BoundHostedSource.doGetVersions
===== asynchronous gap ===========================
package:pub/src/source.dart 169                                                                BoundSource.getVersions
package:pub/src/solver/version_solver.dart 237                                                 SolverCache.getVersions.<fn>
dart:async                                                                                     runZoned
package:pub/src/http.dart 274                                                                  withDependencyType
package:pub/src/solver/version_solver.dart 236                                                 SolverCache.getVersions
===== asynchronous gap ===========================
package:pub/src/solver/unselected_package_queue.dart 121                                       UnselectedPackageQueue._getNumVersions
===== asynchronous gap ===========================
package:pub/src/solver/unselected_package_queue.dart 50                                        UnselectedPackageQueue.add
===== asynchronous gap ===========================
package:pub/src/solver/version_selection.dart 88                                               VersionSelection._addDependencies
===== asynchronous gap ===========================
package:pub/src/solver/version_selection.dart 63                                               VersionSelection.select
===== asynchronous gap ===========================
package:pub/src/solver/backtracking_solver.dart 174                                            BacktrackingSolver.solve
===== asynchronous gap ===========================
package:pub/src/solver/version_solver.dart 42                                                  resolveVersions.<fn>
package:pub/src/log.dart 409                                                                   progress
package:pub/src/solver/version_solver.dart 40                                                  resolveVersions
package:pub/src/entrypoint.dart 206                                                            Entrypoint.acquireDependencies
===== asynchronous gap ===========================
package:pub/src/command/upgrade.dart 41                                                        UpgradeCommand.run
===== asynchronous gap ===========================
package:args/command_runner.dart 194                                                           CommandRunner.runCommand
===== asynchronous gap ===========================
package:pub/src/command_runner.dart 167                                                        PubCommandRunner.runCommand.<fn>
dart:async                                                                                     new Future.sync
package:pub/src/utils.dart 103                                                                 captureErrors.<fn>
dart:async                                                                                     runZoned
package:pub/src/utils.dart 122                                                                 captureErrors
package:pub/src/command_runner.dart 167                                                        PubCommandRunner.runCommand
===== asynchronous gap ===========================
package:pub/src/command_runner.dart 116                                                        PubCommandRunner.run
===== asynchronous gap ===========================
E:\b\build\slave\Windows_Engine\build\src\third_party\dart\third_party\pkg\pub\bin\pub.dart 8  main
This is an unexpected error. Please run

    pub --trace upgrade --verbosity=normal --no-packages-dir

and include the logs in an issue on https://github.com/dart-lang/pub/issues/new
C:\src\flutter\flutter\packages\flutter_tools [roll-engine-20180322 ≡]>