[Solved]-React-Redux: Actions must be plain objects. Use custom middleware for async actions Error-Reactjs

Your action looks like it is using redux-thunk but your config says otherwise.

I'm new to react as well so I'm not 100% sure, but try this configuration (after installing redux-thunk of course):

import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import { createStore, applyMiddleware } from 'redux';
import thunk from 'redux-thunk';
import ReduxPromise from 'redux-promise';

import App from './components/app';
import reducers from './reducers';

const createStoreWithMiddleware = applyMiddleware(thunk, ReduxPromise)(createStore);

ReactDOM.render(
  <Provider store={createStoreWithMiddleware(reducers)}>
    <App />
  </Provider>,
  document.querySelector('.container')
);

A great article that can help is redux 4 ways.

Regarding the code.

With redux-promise (which I see that you are using now) you should write:

export const getNewsAPI = () => {
  return {
      type: 'API_REQUEST',
      options: {
        method: 'GET',
        endpoint: `https://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=${API_KEY}`,
        actionTypes: {
          success: types.GET_NEWS_API_SUCCESS,
          error: types.GET_NEWS_API_ERROR
        }
      }

Or, with redux-thunk:

Instead of:

export const getNewsAPI = () => {
  return (dispatch, getState) => {
    dispatch({
      type: 'API_REQUEST',
      options: {
        method: 'GET',
        endpoint: `https://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=${API_KEY}`,
        actionTypes: {
          success: types.GET_NEWS_API_SUCCESS,
          error: types.GET_NEWS_API_ERROR
        }
      }
    });
  }
}

Use:

function actionCreator() {
  return {
          type: 'API_REQUEST',
          options: {
            method: 'GET',
            endpoint: `https://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=${API_KEY}`,
            actionTypes: {
              success: types.GET_NEWS_API_SUCCESS,
              error: types.GET_NEWS_API_ERROR
            }
          }  
      }
}

and:

export const getNewsAPI = () => {
  return function (dispatch) {
    dispatch(actionCreator())
    }