即使我设置了路由,也没有定义路由

I have a signup form and a login form in one page:

            <div class="col-md-6 col-centered col-reg">
            <h2>Registreer</h2>
            <form method="post" action="{{ route('signup') }}">
                <div class="form-group {{ $errors->has('regName') ? 'has-error' : '' }}">
                    <label>Naam</label> @if($errors->has('regName')) <span style="color: darkred;">{{ $errors->first('regName') }}</span> @endif<br>
                    <input type="text" name="regName" class="form-control" value="{{ old('regName') }}">
                </div>
                <div class="form-group {{ $errors->has('regEmail') ? 'has-error' : '' }}">
                    <label>Email</label> @if($errors->has('regEmail')) <span style="color: darkred;">{{ $errors->first('regEmail') }}</span> @endif<br>
                    <input type="email" name="regEmail" class="form-control" value="{{ old('regEmail') }}">
                </div>
                <div class="form-group {{ $errors->has('regPassword') ? 'has-error' : '' }}">
                    <label>Wachtwoord</label> @if($errors->has('regPassword')) <span style="color: darkred;">{{ $errors->first('regPassword') }}</span> @endif<br>
                    <input type="password" name="regPassword" class="form-control">
                </div>
                <div class="form-group {{ $errors->has('password_confirmation') ? 'has-error' : '' }}">
                    <label>Nogmaals Wachtwoord</label> @if($errors->has('password_confirmation')) <span style="color: darkred;">{{ $errors->first('password_confirmation') }}</span> @endif<br>
                    <input type="password" name="password_confirmation" class="form-control">
                </div>
                <input type="submit" value="Registreer" name="regSubmit" class="btn btn-primary">
                <input type="hidden" name="_token" value="{{ Session::token() }}">
            </form>
        </div>
        <div class="col-md-6 col-centered col-log">
            <h2>Login</h2>
            <form method="post" action="{{ route('login') }}">
                <div class="form-group">
                    <label>Email</label><br>
                    <input type="email" name="logEmail" class="form-control">
                </div>
                <div class="form-group">
                    <label>Wachtwoord</label><br>
                    <input type="password" name="logPassword" class="form-control">
                </div>
                <input type="submit" value="Login" name="logSubmit" class="btn btn-primary">
                <input type="hidden" name="_token" value="{{ Session::token() }}">
            </form>
        </div>

And in the form action I have linked a route and set them in my web.php, like this:

Route::group(["prefix" => "forms"], function() {
   Route::post('/', 'PostController@login')->name('login');
   Route::post('/', 'PostController@signUp')->name('signup');
});

But I get an error message like this:

Route [login] not defined

Even though I created them in my web.php and grouped them.

My route list:

Route List

Why do I get this error? (New to laravel by the way)

You've defined 2 routes with the same Request Method and with the same Route, that just doesn't add along, try:

Route::post('/login', 'PostController@login')->name('login');

If you dont want to change your login URL you can change url of your register route, but the point is that you can't have two routes with the same Request Method and same URL.