<h2 dir="auto">Steps to Reproduce</h2>
<p dir="auto">Run <code class="notranslate">flutter doctor</code> after downloading flutter.</p>
<h2 dir="auto">Logs</h2>
<p dir="auto">None, it's failing on doctor.</p>
<h2 dir="auto">Flutter Doctor</h2>
<p dir="auto">Updating flutter tool...<br>
FINE: Pub 2.0.0-edge.0d5cf900b021bf5c9fa593ffa12b15bcd1cc5fe0<br>
IO  : Spawning "cmd /c ver" in C:\flutter\packages\flutter_tools.<br>
IO  : Finished ver. Exit code 0.<br>
| stdout:<br>
| |<br>
| | Microsoft Windows [versÃ£o 10.0.16299.248]<br>
| Nothing output on stderr.<br>
MSG : Resolving dependencies...<br>
SLVR: Solving dependencies:<br>
| - coverage 0.10.0 from hosted (coverage)<br>
| - test 0.12.30+3 from hosted (test)<br>
| - file 2.3.6 from hosted (file)<br>
| - mustache 1.0.0 from hosted (mustache)<br>
| - meta 1.1.2 from hosted (meta)<br>
| - web_socket_channel 1.0.7 from hosted (web_socket_channel)<br>
| - http 0.11.3+16 from hosted (http)<br>
| - xml 2.6.0 from hosted (xml)<br>
| - json_rpc_2 2.0.7 from hosted (json_rpc_2)<br>
| - stream_channel 1.6.3 from hosted (stream_channel)<br>
| - process 2.0.7 from hosted (process)<br>
| - vm_service_client 0.2.4+1 from hosted (vm_service_client)<br>
| - front_end any from hosted (front_end)<br>
| - linter 0.1.43 from hosted (linter)<br>
| - quiver 0.28.0 from hosted (quiver)<br>
| - args 1.3.0 from hosted (args)<br>
| - package_config 1.0.3 from hosted (package_config)<br>
| - crypto 2.0.2+1 from hosted (crypto)<br>
| - platform 2.1.2 from hosted (platform)<br>
| - plugin 0.2.0+2 from hosted (plugin)<br>
| - stack_trace 1.9.1 from hosted (stack_trace)<br>
| - usage 3.3.0 from hosted (usage)<br>
| - intl 0.15.2 from hosted (intl)<br>
| - archive 1.0.33 from hosted (archive)<br>
| - cli_util 0.1.2+1 from hosted (cli_util)<br>
| - json_schema 1.0.8 from hosted (json_schema)<br>
| - yaml 2.1.13 from hosted (yaml)<br>
| - analyzer any from hosted (analyzer)<br>
IO  : Get versions from <a href="https://pub.dartlang.org/api/packages/coverage" rel="nofollow">https://pub.dartlang.org/api/packages/coverage</a>.<br>
IO  : HTTP GET <a href="https://pub.dartlang.org/api/packages/coverage" rel="nofollow">https://pub.dartlang.org/api/packages/coverage</a><br>
| Accept: application/vnd.pub.v2+json<br>
| X-Pub-OS: windows<br>
| X-Pub-Command: upgrade<br>
| X-Pub-Session-ID: 4536270E-0F24-47AF-975D-67B3DAA7A98C<br>
| X-Pub-Environment: :flutter_install<br>
| X-Pub-Reason: direct<br>
| user-agent: Dart pub 2.0.0-edge.0d5cf900b021bf5c9fa593ffa12b15bcd1cc5fe0<br>
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...</p>
<p dir="auto">This gets looped continuously.</p>
<blockquote>
<p dir="auto">ubuntu 17.04</p>
</blockquote>
<h2 dir="auto">环境搭建遇到错误</h2>
<div class="highlight highlight-source-shell notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="git clone -b alpha https://github.com/flutter/flutter.git"><pre class="notranslate">git clone -b alpha https://github.com/flutter/flutter.git</pre></div>
<div class="highlight highlight-source-shell notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="evanyan@ps:~$ flutter doctor
Building flutter tool...
The setter 'readEventsEnabled=' was called on null.
Receiver: null
Tried calling: readEventsEnabled=false
package:pub/src/source/hosted.dart 338                    BoundHostedSource._throwFriendlyError
package:pub/src/source/hosted.dart 140                    BoundHostedSource.doGetVersions
===== asynchronous gap ===========================
package:pub/src/source.dart 165                           BoundSource.getVersions
package:pub/src/solver/version_solver.dart 231            SolverCache.getVersions.&lt;fn&gt;
dart:async                                                runZoned
package:pub/src/http.dart 228                             withDependencyType
package:pub/src/solver/version_solver.dart 230            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 68          VersionSelection.select.&lt;fn&gt;
===== asynchronous gap ===========================
dart:async                                                _completeOnAsyncReturn
package:pub/src/solver/version_selection.dart 70          VersionSelection.select.&lt;fn&gt;
dart:async                                                _completeOnAsyncReturn
package:pub/src/solver/unselected_package_queue.dart 54   UnselectedPackageQueue.add
dart:async                                                _completeOnAsyncReturn
package:pub/src/solver/unselected_package_queue.dart 128  UnselectedPackageQueue._getNumVersions
dart:async                                                _Completer.completeError
package:pub/src/solver/version_solver.dart 254            SolverCache.getVersions
dart:async                                                _Completer.completeError
package:pub/src/source/hosted.dart 153                    BoundHostedSource.doGetVersions
dart:async                                                _Completer.completeError
package:http/src/base_client.dart 172                     BaseClient._sendUnstreamed
dart:async                                                _Completer.completeError
package:http_throttle/http_throttle.dart 51               ThrottleClient.send
dart:async                                                _Completer.completeError
package:pub/src/http.dart 127                             _PubHttpClient.send
dart:async                                                _Completer.completeError
package:http/src/io_client.dart 66                        IOClient.send
This is an unexpected error. Please run

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

and include the logs in an issue on https://github.com/dart-lang/pub/issues/new
Error: Unable to pub upgrade flutter tool. Retrying in five seconds..."><pre class="notranslate">evanyan@ps:<span class="pl-k">~</span>$ flutter doctor
Building flutter tool...
The setter <span class="pl-s"><span class="pl-pds">'</span>readEventsEnabled=<span class="pl-pds">'</span></span> was called on null.
Receiver: null
Tried calling: readEventsEnabled=false
package:pub/src/source/hosted.dart 338                    BoundHostedSource._throwFriendlyError
package:pub/src/source/hosted.dart 140                    BoundHostedSource.doGetVersions
===== asynchronous gap ===========================
package:pub/src/source.dart 165                           BoundSource.getVersions
package:pub/src/solver/version_solver.dart 231            SolverCache.getVersions.<span class="pl-k">&lt;</span>fn<span class="pl-k">&gt;</span>
dart:async                                                runZoned
package:pub/src/http.dart 228                             withDependencyType
package:pub/src/solver/version_solver.dart 230            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 68          VersionSelection.select.<span class="pl-k">&lt;</span>fn<span class="pl-k">&gt;</span>
===== asynchronous gap ===========================
dart:async                                                _completeOnAsyncReturn
package:pub/src/solver/version_selection.dart 70          VersionSelection.select.<span class="pl-k">&lt;</span>fn<span class="pl-k">&gt;</span>
dart:async                                                _completeOnAsyncReturn
package:pub/src/solver/unselected_package_queue.dart 54   UnselectedPackageQueue.add
dart:async                                                _completeOnAsyncReturn
package:pub/src/solver/unselected_package_queue.dart 128  UnselectedPackageQueue._getNumVersions
dart:async                                                _Completer.completeError
package:pub/src/solver/version_solver.dart 254            SolverCache.getVersions
dart:async                                                _Completer.completeError
package:pub/src/source/hosted.dart 153                    BoundHostedSource.doGetVersions
dart:async                                                _Completer.completeError
package:http/src/base_client.dart 172                     BaseClient._sendUnstreamed
dart:async                                                _Completer.completeError
package:http_throttle/http_throttle.dart 51               ThrottleClient.send
dart:async                                                _Completer.completeError
package:pub/src/http.dart 127                             _PubHttpClient.send
dart:async                                                _Completer.completeError
package:http/src/io_client.dart 66                        IOClient.send
This is an unexpected error. Please run

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

and include the logs <span class="pl-k">in</span> an issue on https://github.com/dart-lang/pub/issues/new
Error: Unable to pub upgrade flutter tool. Retrying <span class="pl-k">in</span> five seconds...</pre></div>