Unexpected end of json input

As i was using ionic3 procject working and still apk working well . Ionic auto v4 updated and now i get this error " Unexpected end of JSON input"

i using mysql beckend

i changed ionic version 4 to 3.4 , but still i get same error. how can fix it

I unable to solve it ,anyone know please teach me i will appreciate~

login.ts

login(){
   if(this.userData.username && this.userData.password){
    this.authService.postData(this.userData, "login").then((result) =>{
    this.resposeData = result;

auth.service.ts

 postData(credentials, type){

    return new Promise((resolve, reject) =>{
      let headers = new Headers();
      this.http.post(apiUrl+type, JSON.stringify(credentials), {headers: headers}).
      subscribe(res =>{
        resolve(res.json());
      }, (err) =>{
        reject(err);
      });

    });

  }

anyone help me. i am very misarable

Try adding the debugger line. Run it in a browser and see what is contained in the res variable to give you an idea.

return new Promise((resolve, reject) =>{
      let headers = new Headers();
      this.http.post(apiUrl+type, JSON.stringify(credentials), {headers: headers}).
      subscribe(res =>{
        debugger; <--
        resolve(res.json());
      }, (err) =>{
        reject(err);
      });

    });

Unsubscribe error.
What do you think it might be causing an error

Server is rejecting your auth attempt I think

I fix the unexpected end of json input problem. no need of promise with v4 but another problem occurred.

If i start project on development mod on web or mobile i get this error

Cross-Origin Read Blocking (CORB) blocked cross-origin response http://katalog.forev.com.tr/PHP-Slim-Restful-master/api/login with MIME type text/html. See https://www.chromestatus.com/feature/5629709824032768 for more details.

I used chrome extension allow control allow origin but it didnt work
And my php beckend sql header conf.

Header add Access-Control-Allow-Origin "*"
Header add Access-Control-Allow-Headers " content-type"
Header add Access-Control-Allow-Methods "PUT, GET, POST, DELETE, OPTIONS"

There was no such error in the ioniv v3

I generate android apk and try on apk, no error . work well. i really understand.

This is googles doing. It’s a new security feature added to the browser. Trust me your ionic 3 projects will go through the same thing when served on the browser.

At some point in time during your development your machine updated your chrome browser to 67+ (I think 73 is when they literally just start blocking json altogether). And this version is where the CORB or cross-origin read blocking feature starts.

I’m still trying to figure out a way around this but hopefully, the angular team may have an answer soon (At least ionic 4 can be saved).