javascript fetch - Failed to execute 'json' on 'Response': body stream is locked

Question

When the request status is greater than 400(I have tried 400, 423, 429 states), fetch cannot read the returned json content. The following error is displayed in the browser cons

Answer 1

I met this error too but found out it is not related to the state of Response, the real problem is that you only can consume Response.json() once, if you are consuming it more than once, the error will happen.

like below:

    fetch('http://localhost:3000/movies').then(response =>{
    console.log(response);
    if(response.ok){
         console.log(response.json()); //first consume it in console.log
        return response.json(); //then consume it again, the error happens

    }

So the solution is to avoid consuming Response.json() more than once in then block.