"The GET method is not supported for this route. Supported methods: POST."

I tried to solve this problem "The GET method is not supported for this route. Supported methods: POST."

    var get_and_read = function () {
        message = messages.shift();
        //console.log(message.id);
        var sender = {id: message.id, _token: ''};
        $.ajax({
            type: 'POST',
            url: "",
            data: sender
        });
        return message;
    }

In my web.php

Route::post('/widgets/alertbox/read', 'AlertboxController@postMessage')->name('alertbox.post');

In my controller

public function postMessage(Request $request) {

    $message = DB::table('message')->update('status', 'success')->where('phone_number', $request->id)->first();

    if (!$message)
        abort(403);
}

When function get_and_read was called

500 Internal server error

via Chebli Mohamed