Laravel Fix Error : Function name must be a string by Illuminate\Pipeline\Pipeline.php

Issue: Laravel encountered error "Function name should be a string" or "Function name must be a string" in Api or somewhere. Error reported from file "Illuminate\Pipeline\Pipeline.php"

$carry = method_exists($pipe, $this->method)

                                    ? $pipe->{$this->method}(...$parameters)

                                    : $pipe(...$parameters);

Reason: You have used some middleware by name that has not been previously declared.

Debug: Check all middleware used, make sure it is already declared in the file Kernel.php. The most common scenario is that you have not declared 'auth' middleware yet.

protected $routeMiddleware = [

        'auth' => \Illuminate\Auth\Middleware\Authenticate::class,

        ...

}

Done !