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TypeError: Network Request Failed when trying to hit local API from android emulator. React-Native

I've seen answers to this question everywhere but none of them seem to work for me.
I'm trying to do a react native fetch from my android emulator and hit my local API running on https://localhost:5002/v1/users.
This is what my fetch looks like right now:
var response: Response = await fetch(`https://10.0.2.2:5002/v1/user/${initialContext.userId}`, {
method: "GET",
headers: {
"Authorization": `Bearer ${initialContext.accessToken}`
}
});
and this is the error that I'm getting:
Possible Unhandled Promise Rejection (id: 0):
TypeError: Network request failed
TypeError: Network request failed
at C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:26139:20
at C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:30727:21
at _callTimer (C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:30643:9)
at Object.callTimers (C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:30851:9)
at MessageQueue.__callFunction (C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:2781:31)
at C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:2513:17
at MessageQueue.__guard (C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:2735:13)
at MessageQueue.callFunctionReturnFlushedQueue (C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\index.bundle:2512:14)
at C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\debuggerWorker.js:199:58
at process.<anonymous> (C:\Users\raffaele.leo\Downloads\Source-Code\cbt-systems\1.x\trunk\src\CBTravel.Mobile.AirPortal\.vscode\.react\debuggerWorker.js:68:9)
As you can see I've tried running it with 10.0.2.2 (the local host equivalent for the emulator) and I've also tried my computer's IP address. I've also tried running adb reverse and other port forwarding methods.
The hardest part for me to wrap my head around is that if I go to https://10.0.2.2:5002 on chrome on my emulator I'm able to hit my local API. I'm also able to hit an API in the cloud from that fetch statement, just not anything running on local host.
Any ideas would be appreciated.

Actually it's easy to work using ngrok, which acts in between your emulator and localhost(network tunnelling). It provides you with a domain and forwards all your requests to localhost.
You can check this documentation https://ngrok.com/docs

Why can't I 'fetch' some URLs from my Capacitor app on Android?

I'm trying to write a mobile app via Capacitor that makes use of PouchDB. When I run the app in the emulator via Android Studio the connection to the remote CouchDB instance fails. I've tracked this down to a failure in the fetch API for certain URLs when running on Android.
To debug I made a minimal web application and wrapped it using Capacitor to run on Android. The app includes the following code
const testFetch = (url) => {
console.log("Testing fetch", url)
fetch(url)
.then((response) => response.text())
.then((t) => {
console.log("Respose from fetch:", url)
console.log(t)
console.log("that was it")
})
.catch((reason) => {
console.log("FETCH FAILED", url, reason)
})
}
I then have three tests:
testFetch("https://jsonplaceholder.typicode.com/todos/1"); // just some JSON
testFetch("http://10.0.2.2:5984/simple"); // local pouchdb instance
testFetch("http://10.0.2.2:8080/sample.json"); // local http server + CORS
The second two use the IP address that is an alias for the development machine when running in the Android emulator. I confirmed that I can access all of these URLs from the browser on the emulator but the app succeeds on the first and fails on the second two (error: TypeError: Failed to fetch). When running the base web app in the browser, all succeed (with localhost instead of 10.0.2.2).
CORS headers are in place on all URLs. As far as I can see the app doesn't even try to access the two servers that fail - no HEAD requests for example. I've also tried various other URLs and can't see a pattern to the failures -- eg. it's not the port number != 80.
Any clues as to what is going on would be appreciated.

So the thing I didn't notice that the failing URLs had in common was http rather than https. It turns out that fetch silently fails to work for any http URL, just giving the error 'Failed to fetch'.
I'm not sure whether this is a feature of the Android web view or of Capacitor itself. The Capacitor docs suggest that using https is a good idea but not that http won't work.
This policy doesn't get altered by setting a Content Security Policy in the main page header.
The original goal was to connect a local PouchDB database to a remote CouchDB instance. This now works as long as the CouchDB instance is served via https. Without that you just get silent failure to sync.

How do I get http content from a https website?

I get "Http failure response for https://www.google.com: 0 Unknown Error" when I request from Secured url.
I am trying to test my ionic/angular mobile app. When I tried with http requests I had problem with Android 9, but with Android 7 was working fine. Anyhow I need to set my backend to public https server. So now I'm testing with https request and none of 7 and 9 Android versions works.
I am using Angular 7 ,
"#ionic/angular": "^4.6.1",
"#ionic-native/core": "^5.0.0",
"rxjs": "~6.5.1"
I made these small functions in order to make my problem simpler.
inside my html file i have this code:
myFile.html
<ion-button
(click)="onStartTest()"
>Click me</ion-button>
<p id="testme"></p>
myFile.page.ts
onStartTest() {
this.taskService.onTest().subscribe(result => {
document.getElementById('testme').innerText = 'result ' + result;
console.log(result);
}, error => {
document.getElementById('testme').innerText = error.message;
console.log('Problem ', error.message);
});
}
myTask.service.ts
onTest() {
return this.http.get('https://www.google.com').pipe(
catchError(err => {
return throwError(err);
})
);
}
At first I tried my server's URL but I changed it to "https://www.google.com" just to verify that the backend is correct.
Also I have an interceptors.ts file that I am using it for authentication, but I am not logged in when I execute the onStartTest() function, but im gonna share it anw.
interceptors.ts
import {Injectable} from '#angular/core';
import {HttpEvent, HttpHandler, HttpInterceptor, HttpRequest} from '#angular/common/http';
import {Observable} from 'rxjs';
#Injectable()
export class TokenInterceptor implements HttpInterceptor {
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
const token = localStorage.getItem('auth_token');
let newHeaders = req.headers;
if (token) {
console.log(token);
newHeaders = newHeaders.set('Authorization', 'Token ' + token);
const modified = req.clone({
headers: newHeaders
});
return next.handle(modified);
} else {
newHeaders = newHeaders.set('Content-Type', 'application/json');
const modified = req.clone({
headers: newHeaders
});
return next.handle(modified);
}
}
}
I think these are the necessary files to share for this problem.
I also tested the url of google with Postman just to be sure that I should get a status 200
I am also aware that there is an "add_header" directive (nginx) that adds 'Allow-access-control-origin' when the response code is 20x or 30x. According to my screenshot with Postman, google is responding with 200 status, but my app still gets status 0 error.
Ignore the first Error. It's a function I use with http when the app begins. Right now im testing https.
I tried superficially to use ionic-native library HTTP but my app totally crashed.
I also execute the command ionic serve --ssl but still nothing.
I read somewhere that for secured connection I need a certificate, but I understood that this is a server's work.
I tried to request from Dark Sky from Vanilla JavaScript and it works fine. So there is something wrong with angular/ionic side and not server's.
What am I missing? I really need to fix this problem soon!
I want to send a secured request to an https url and get the appropriate response.

Your main problem is that you are trying make an API to an unsecure call (http) location (http://192....../mobile/tasks) from a secure origin (https://localhost:8100).
This is clearly indicated in your error message and this is not allowed, and has been answered before
Your second problem is that, for testing purposes, you are trying to call a 3rd party https ressource from your website. This only works if the 3rd party ressource implement CORS, which is not the case for Google and api.darksky.net. Sending a GET request with Postman is useless, as Postman will not check for CORS headers before displaying the response. If you want to use Postman to check CORS, send an OPTIONS request to these ressources and you'll see that there are no CORS headers

So the answer is in MDN - CORS
For security reasons, browsers restrict cross-origin HTTP requests
initiated from scripts. For example, XMLHttpRequest and the Fetch API
follow the same-origin policy. This means that a web application using
those APIs can only request resources from the same origin the
application was loaded from, unless the response from other origins
includes the right CORS headers.
This means the back-end I was using needed some more configuration since I was using 'same-origin' policy script. I thought we had it because when we tried from the browser's console to fetch the request it was working fine, but on mobile it wasn't. We had a custom CORS configuration but we changed it to the django-cors-headers. Since we switched to django-cors-headers I could get correctly the response from HTTP and HTTPs requests.
The other answer and comments were really useful to focus to the right direction.

react native Fetch Network request failed on android

I'm trying to receive some simple json from mocky.
React native fetch function:
getMemberDomainList = async (name) => {
try {
let response = await fetch('https://5c9cc9ed3be4e30014a7d287.mockapi.io/api/domain', {
method: 'POST',
headers: {
Accept: 'application/json',
'Content-Type': 'application/json',
},
});
let responseJson = await response.json();
return responseJson;
} catch (error) {
console.error(error);
}
}
I have tested the address in chrome on windows, it returns the expected mock data. But when the function is called on my android phone I get this error
Error from remote debugger
...\node_modules\react-native\Libraries\Renderer\oss\ReactNativeRenderer-dev.js:2348 TypeError: Network request failed
at XMLHttpRequest.xhr.onerror (...\Libraries\Renderer\oss\ReactNativeRenderer-dev.js:4337)
at XMLHttpRequest.dispatchEvent (...\Libraries\Renderer\oss\ReactNativeRenderer-dev.js:10760)
at XMLHttpRequest.setReadyState (...\Libraries\Renderer\oss\ReactNativeRenderer-dev.js:10511)
at XMLHttpRequest.__didCompleteResponse (...\Libraries\Renderer\oss\ReactNativeRenderer-dev.js:10343)
at ...\Libraries\Renderer\oss\ReactNativeRenderer-dev.js:10449
at RCTDeviceEventEmitter.emit (...\Libraries\Components\DrawerAndroid\DrawerLayoutAndroid.android.js:11)
at MessageQueue.__callFunction (...\Libraries\ART\ReactNativeART.js:362)
at blob:http://localhost:8081/79251787-d190-4650-8040-23d091c08738:2334
at MessageQueue.__guard (...\Libraries\ART\ReactNativeART.js:312)
at MessageQueue.callFunctionReturnFlushedQueue (...\Libraries\ART\ReactNativeART.js:139)
I'm also running a WebView in my app, which is pointing to a web url, it loads perfectly so I am sure that the phone has internet permission and access etc.

In the latest android versions http requests are not allowed by default. Take a look at this post for further information about allowing http request: How to allow all Network connection types HTTP and HTTPS in Android (9) Pie?

Can't get mockapi.io to work. But the error is not persistent when using services such as:
https://jsonplaceholder.typicode.com/todos/1
Might not be an android or react native related problem after all. Also had issues with mockapi.io in postman, though it works fine in chrome.

If you are using emulator then check whether internet is working or not in this emulation using browser. If not check this: Android emulator not able to access the internet
I have also face this problem in emulator but when I generate a release app and install in a real device(andoid 9) then it works fine.

Please check backend response status.
If backend is sending contents using 205 status - 205 RESET CONTENT
Android system recognize it as an error - HTTP 205 had non-zero Content-Length: 25.
You can check the status code on postman.
So, in this case, the error should be fixed on backend.
It should send contents with 200 status code.

React-native - Axios GET request throws network error in Android emulator

I am new to React-native. I am trying to perform a simple get request using the following code:
axios.get('http://push-cycling-backend.dev/api/test')
.then((response) => {
console.log(response);
})
.catch((error) => {
console.log(error);
});
I have tested the request using Postman and everything works fine, but when I run the request in my react-native app using the ANDROID EMULATOR, I get the following error:
Error: Network Error
I have a feeling this is because I am trying to access a Api end point hosted locally through Xammp via the Android emulator, but I have no idea what to do.
Please any guidance would be greatly appreciated.
Kind regards,
Matt

I managed to get it working by changing the request URL from http://push-cycling-backend.dev/api/test to http://10.0.2.2:80/push-cycling-backend/public/api/test. From what i understand, since the android emulator, emulates a actual device, I believe 'localhost' was referring to an address on the emulated device instead of my local server 10.0.2.2 is something like a keyword that refers to your local machines ip address.