Registring a middleware but the MYSQL is not working

Question

Dear all when i register my middleware in kernel file in Laravel 8 there is no MYSQL is working kindly help me i register in this group

 protected $middlewareGroups = [
        'web' => [
            \App\Http\Middleware\EncryptCookies::class,
            \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
            \Illuminate\Session\Middleware\StartSession::class,
            // \Illuminate\Session\Middleware\AuthenticateSession::class,
            \Illuminate\View\Middleware\ShareErrorsFromSession::class,
            \App\Http\Middleware\VerifyCsrfToken::class,
            \Illuminate\Routing\Middleware\SubstituteBindings::class,
        ],

and my middle ware is

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;

class CheckUser
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle(Request $request, Closure $next)
    {
        echo "Middle ware is implemented successfully";
        return $next($request);
    }
}

Kindly help me how to get out from that i am developing an app