Unable to 'pub upgrade'

第三次入门Flutter 希望这次能坚持下来,

执行Flutter doctor

Building flutter tool...

Unhandled exception:

Bad state: Future already completed

#0 _AsyncCompleter.complete (dart:async/future_impl.dart:39:31)

#1 _NativeSocket.startConnect.<anonymous closure>.connectNext.<anonymous closure> (dart:io/runtime/binsocket_patch.dart:490:23)

#2 _NativeSocket.issueWriteEvent.issue (dart:io/runtime/binsocket_patch.dart:844:14)

#3 _NativeSocket.issueWriteEvent (dart:io/runtime/binsocket_patch.dart:851:12)

#4 _NativeSocket.multiplex (dart:io/runtime/binsocket_patch.dart:872:11)

#5 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)

Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds... (9 tries left)

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原因是 git clone 下来的flutter 有问题 我的大小 是199M 实际是900多M 重新git clone  好使