Google App Engine: upload_data fails because “target machine actively refused it” on devserver

I'm trying to upload data from a CSV to my app using the devserver:

appcfg.py upload_data --config_file="DataLoader.py" --filename="data.csv" --kind=Foo --url=http://localhost:8083/remote_api "path/to/app"

结果:

Application: appname; version: 1.
Uploading data records.
[INFO    ] Logging to bulkloader-log-20100626.181045
[INFO    ] Throttling transfers:
[INFO    ] Bandwidth: 250000 bytes/second
[INFO    ] HTTP connections: 8/second
[INFO    ] Entities inserted/fetched/modified: 20/second
[INFO    ] Batch Size: 10
[INFO    ] Opening database: bulkloader-progress-20100626.181045.sql3
Please enter login credentials for localhost
Email: email@domain.com
Password for email@domain.com:
[INFO    ] Connecting to localhost:8083/remote_api
[INFO    ] Starting import; maximum 10 entities per post
Google\google_appengine\google\appengine\api\datastore_types.py:673: DeprecationWarning: object.__init__() takes no parameters
  super(Link, self).__init__(self, link)
............[INFO    ] Unexpected thread death: WorkerThread-7
[INFO    ] An error occurred. Shutting down...
........[ERROR   ] Error in WorkerThread-1: <urlopen error [Errno 10061] No connection could be made because the target machine actively refused it>
[ERROR   ] Error in WorkerThread-7: <urlopen error [Errno 10061] No connection could be made because the target machine actively refused it>

[INFO    ] 1230 entites total, 0 previously transferred
[INFO    ] 200 entities (218274 bytes) transferred in 25.8 seconds
[INFO    ] Some entities not successfully transferred

在我尝试后续时间时,传输的实体数在200-850之间。

What is going on here? Normally this works fine. 导航到 http://localhost:8083/ 工作正常,应用程序运行正常。(除了缺乏数据。)