nextjs-handler-allow-methods-middleware.ts

//file: ./pages/api/checkHTTPMethod.ts

/* this code will allow only GET method requests on this route */

import { Middleware, use } from 'next-api-route-middleware';
import type { NextApiRequest, NextApiResponse } from 'next';


export const allowMethods = (allowedMethods: string[]): Middleware => {
    return async function (req, res, next) {
      if (allowedMethods.includes(req.method!) || req.method == 'OPTIONS') {
        next();
      } else {
        res.status(405).send({ message: 'Method not allowed.' });
      }
    };
  };

  const handler: any = (req: NextApiRequest, res: NextApiResponse) => {
     res.status(200).send({ message: 'Voila! No error!' });
  }

  export default use(allowMethods(['GET']), handler);

Thanks. Solved my problem.