Note the following problems encountered with Flutter Upgrade in CMD on Windows 7.

1. An error:

Unblock-File <<<< -Path ‘D:\flutter/bin/internal/update_dart_sdk.ps1

‘; & ‘D: \ flutter/bin/internal/update_dart_sdk ps1’

CategoryInfo : ObjectNotFound: (Unblock-File:String) [], Comman

dNotFoundException

FullyQualifiedErrorId : CommandNotFoundException

When encountering this problem, please check the version of Powershell in Win system. If version 2 is used, this problem will occur. When I upgrade to version 5, the problem will be solved.

2. An error:

Invoke-webrequest: Request aborted: FAILED to create SSL/TLS secure channel. Position D:\flutter\bin\internal\update_dart_sdk.ps1:62 character: 5

  • Invoke-WebRequest -Uri
    d a r t S d k U r l − O u t F i l e dartSdkUrl -OutFile     dartSdkZip +

  • CategoryInfo: InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke – WebRequest], WebExce ption

  • FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeWebRequestCommand

The following two user variables are not present in the environment variable, or the FLUTTER_STORAGE_BASE_URL user variable has been changed to another mirror address

PUB_HOSTED_URL  pub.flutter-io.cn

FLUTTER_STORAGE_BASE_URL storage.flutter-io.cn