解決辦法：

1、打開默認安裝路徑

C:\Users\Administrator\AppData\Local\Atlassian\SourceTree

2、新建accounts.json

[  
  {  
    "$id": "1",  
    "$type": "SourceTree.Api.Host.Identity.Model.IdentityAccount, SourceTree.Api.Host.Identity",  
    "Authenticate": true,  
    "HostInstance": {  
      "$id": "2",  
      
 
"$type": "SourceTree.Host.Atlassianaccount.AtlassianAccountInstance, SourceTree.Host.AtlassianAccount",  
      "Host": {  
        "$id": "3",  
        "$type": "SourceTree.Host.Atlassianaccount.AtlassianAccountHost, SourceTree.Host.AtlassianAccount",  
        "Id": "atlassian account"  
      },  
      
 
"BaseUrl": "https://id.atlassian.com/"  
    },  
    "Credentials": {  
      "$id": "4",  
      "$type": "SourceTree.Model.BasicAuthCredentials, SourceTree.Api.Account",  
      "Username": "",  
      "Email": null  
    },  
    "IsDefault": false  
  }  
]  

3、重新打開，就好了！

SourceTree跳過註冊