If you’re using an Android Emulator then asking for the localhost web service won’t work, because you’re looking at the localhost of the emulator. How can you fix this? Well, Android Emulator has a magic address http://10.0.2.2:your_port that points to 127.0.0.1:your_port on your host machine.Take a look here. Because it points to an IP and not localhost, you need to go into your project solution, in .vs folder->config->applicationhost.config and change this <binding protocol="http" bindingInformation="*:13142:localhost" /> into <binding protocol="http" bindingInformation="*:13142:127.0.0.1" />, where 13142 is my port, yours may be different. Restart IIS Express and you’re good to go.