该错误主要是在您的android AVD或android设备未连接到互联网时发生的.有时，开发人员尝试从android设备而非AVD访问localhost上的插件，在这种情况下，会发生相同的错误.我希望这能解决您的问题.

This error occurs mostly when your android AVD or android device is not connected to internet. Sometimes, the developer tries to access plugin on localhost from android device instead of AVD, in such cases, same error occurs. I hope this solves your problem.

其他情况包括服务器端防火墙阻止了端口.

Other scenarios involves port blocked by firewalls on serverside.

如果您认为我的回答是有用的，请进行投票.

Kindly upvote if you find my answer usable.

学习网络知识