Ktor project localhost:8080 refuses to connect

Question

I was working on a ktor project and everything was working fine. I started the server and it was working fine on port 8080 but now for some reason suddenly it stopped working. I killed the task and tried everything, I'm not sure what's wrong. I tried to reinstall IntelliJ Idea and I'm still facing the same issue. I tried using 127.0.0.1 , 0.0.0.0 , localhost but none of them work idk what to do. I've wasted like 2 hours on this thing. I've tried changing port, blocking firewall and antivirus.

user_12737192 · Answer

change 127.0.0.1(localhost) to your private ip like 172.30.1.59 if you use wifi. if you use fixed ip then use it. i have same problem, but solve it with this. Nice! cmd -> ipconfig -> use ip address

user_13270851 · Answer

I usually had the same issue using Ktor and it is frustrating. Then I am gonna post the following possible fixes that you should try in order and reading the steps. I am going to consider that you are running a WebSocket server and a WebSocket client for your Android app in a unique computer.

You are running the server side and the client using the same ip and it should not work, because the client can not connect to the server. When I am testing a project that requires server-side and client-side I use my computer to run the Android app and the laptop to run the server side. If this is not your case, then, do not pay attention.
In the client-side, when you create the instance of the HttpClient, do you pass any value to the client as engine or you simply go directly with lambda? From my experience, when I create the HttpClient instance, only works these two following first ones:
```
val client = HttpClient {
   install(WebSockets)
}
```
or
```
val client = HttpClient(CIO){
   install(WebSockets)
}
```
The engine that doesn't work for me is:
```
val client = HttpClient(OkHttp) {
   install(WebSockets)
}
```
Finally, when you create the WebSocket using the past client instance, you should use
```
client.ws(
        HttpMethod.Get,
        "localhost",
        8080,
        "/"
)
{
//Client code
}
```
and not client.wss. That is because in local connection, your client do not connect using TLS security and it will throw an exception. If you're deploying your server-side in a hosting that has TLS security as Heroku, then you can use the wss one, because the client-side will connect using TLS certificate.

Hope that my response can help. Good luck!

user_1730966 · Answer

I had the same problem and it turned out that it was because I had the HttpsRedirect and HSTS plugins installed. Due to this it refused to handle the http request and since I don't have any certificate for localhost or my local IP it didn't work.

Disabling these two plugins when running locally makes things work for me.

Ktor project localhost:8080 refuses to connect

3 Answers