Custom module controller not working magento2

Question

I have added a sample custom module in Magento 2. I have two controller function for admin panel page,

http://127.0.0.1/magento2/admin_magento2/sample/index/index/
http://127.0.0.1/magento2/admin_magento2/sample/sampletwo/index/

First url only display page. The second one displays 404 or redirecting to dashboard.

Please help me someone to solve this.

Note

I have added admin panel menu for first url only.

app\code\Test\Sample\Controller\Adminhtml\Index\Index.php

namespace Test\Sample\Controller\Adminhtml\Index;
class Index extends \Magento\Backend\App\Action
{
    public function execute()
    {
        $this->_view->loadLayout();
        $this->_view->getLayout()->initMessages();
        $this->_view->renderLayout();
    }
}

app\code\Test\Sample\Controller\Adminhtml\Sampletwo\Index.php

namespace Test\Sample\Controller\Adminhtml\Sampletwo;
class Index extends \Magento\Backend\App\Action
{
    public function execute()
    {
        $this->_view->loadLayout();
        $this->_view->getLayout()->initMessages();
        $this->_view->renderLayout();
    }
}

app\code\Test\Sample\etc\adminhtml\menu.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../Magento/Backend/etc/menu.xsd">
    <menu>
        <add id="Test_Sample::parent" title="Sample" module="Test_Sample" sortOrder="100" resource="Test_Sample::parent"/>
        <add id="Test_Sample::index" title="Sample Index" module="Test_Sample" sortOrder="10" action="sample/index" resource="Test_Sample::index" parent="Test_Sample::parent"/>
    </menu>
</config>

app\code\Test\Sample\etc\adminhtml\routes.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../../lib/internal/Magento/Framework/App/etc/routes.xsd">
    <router id="admin">
        <route id="sample" frontName="sample">
            <module name="Test_Sample" before="Magento_Adminhtml" />
        </route>
    </router>
</config>

Answer 1

your action should be sample/sampletwo in menu.xml

Answer 2

When attempting to access modules/functionality in the backend (Adminhtml), Magento checks for the presence of the secret Form Keys, and if/when someone does attempt to access an action and doesn't supply a valid FormKey and/or supplies an Invalid FormKey - the Adminhtml AbstractAction (Magento\Backend\App\AbstractAction) will route the user Admin UIX defined Startup page (which is usually the Dashboard page)

[This mechanism serves a "security checkpoint" to prevent users from accessing portions of the Backend that they don't have access to]

---

When accessing options from the Admin UIX Menu - Magento will automatically add the FormKey for you. That is why you are able to access the first URL v/s not able to access the second URL.

---

To prevent the check for FormKey you have two options:

(a) Turn off FormKey Validation

Navigation: Stores -> Settings : Configuration -> Advanced : Admin -> Security -> Setup "Add Secret Key to URLs" to "No"

It's very important to remember that doing so will turn off Secret Key Validation, and therefore may make your application vulnerable.

(b) Turn off FormKey Validation for your controller

Specify the action(s) you wish to exempt, from the FormKey check, in the "$_publicActions" attribute of your Admin Controller.

protected $_publicActions = ['ENTER_NAME_OF_ACTION'];

Code Example:

class Index extends \Magento\Backend\App\Action
{
    protected $_publicActions = ['index'];

    public function execute()
    {
        echo "My Hello World! Controller";
    }

}

Answer 3

app\code\Test\Sample\etc\adminhtml\routes.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="admin">
        <route frontName="test_sample" id="test_sample">
            <module before="Magento_Backend" name="Test_Sample"/>
        </route>
        <route frontName="sampletwo" id="sampletwo">
            <module before="Magento_Backend" name="Test_Sample"/>
        </route>
    </router>
</config>