Magento 2 System Configuration Custom setting for Module not working

Question

I have followed below link and created both "system.xml" and "acl.xml" at their respective locations.

https://stackoverflow.com/questions/32614392/magento-2-system-xml-in-custom-module

But instead of creating a custom system config tab and setting for this module, it gives error as following in a report generated:

a:4:{i:0;s:138:"Notice: Undefined index: id in /var/www/html/magento-2/vendor/magento/module-config/Model/Config/Structure/Element/Iterator.php on line 59";i:1;s:6805:"#0 /var/www/html/magento-2/vendor/magento/module-config/Model/Config/Structure/Element/Iterator.php(59): Magento\Framework\App\ErrorHandler->handler(8, 'Undefined index...', '/var/www/html/m...', 59, Array)

Anyone can clarify what could be the issue?

/Darsh/Banner/etc/adminhtml/system.xml:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../Config/etc/system_file.xsd">
    <system>
        <!-- Add new Tab -->
        <tab id="darsh" translate="label" sortOrder="300">
            <label>Darsh Banner</label>
        </tab>
        <section id="darsh_banner" translate="label" type="text" sortOrder="140" showInDefault="1" showInWebsite="1" showInStore="1">
            <label>Helloworld</label>
            <tab>darsh_banner</tab>
            <!-- resource tag name which we have to defined in the acl.xml -->
            <resource>Darsh_Banner::config_darsh_banner</resource>
        </section>
        <group id="general" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
            <label>General Options</label>
            <field id="active" translate="label" type="select" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>Enabled</label>
                <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
            </field>
        </group>
    </system>
</config>

and /Darsh/Banner/etc/acl.xml:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Acl/etc/acl.xsd">
    <acl>
        <resources>
            <resource id="Magento_Backend::admin">
                <resource id="Magento_Backend::stores">
                    <resource id="Magento_Backend::stores_settings">
                        <resource id="Magento_Config::config">
                            <!-- this resource id we can use in system.xml for section -->
                            <resource id="Darsh_Banner::config_darsh_banner" title="Helloworld Section" sortOrder="80" />
                        </resource>
                    </resource>
                </resource>
            </resource>
        </resources>
    </acl>
</config>

Answer 1

First mistake is .xsd file configuration, In magento 2 stable release it should be

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">

and second mistake is section should be darsh instead of darsh_banner

third mistake is

<tab>darsh_banner</tab> It should be

<tab>darsh</tab>