Magento 2.2.5: Overriding Admin Controller sales/order

I need to override Admin sales/order/index controller, but still getting 404. Below the Steps I take to override –

Created My Custom Module
app/code/A2bizz/Order/registration.php

 <?php \Magento\Framework\Component\ComponentRegistrar::register(     \Magento\Framework\Component\ComponentRegistrar::MODULE,     'A2bizz_Order',     __DIR__ ); 

app/code/A2bizz/Order/etc/module.xml

 <?xml version="1.0"?> <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">     <module name="A2bizz_Order" setup_version="2.0.0" schema_version="2.0.0">         <sequence>             <module name="Magento_Sales"/>             <module name="Magento_Rule"/>             <module name="Magento_Catalog"/>             <module name="Magento_Customer"/>             <module name="Magento_Payment"/>             <module name="Magento_SalesSequence"/>         </sequence>     </module> </config> 

app/code/A2bizz/Order/Controller/Adminhtml/Order/Index.php

 <?php      namespace A2bizz\Order\Controller\Adminhtml\Order;      class Index extends \Magento\Sales\Controller\Adminhtml\Order\Index     {         public function execute()         {             $  this->messageManager->addSuccess('Message from new admin controller.');             // Do your stuff here             return parent::execute();         }     } 

app/code/A2bizz/Order/etc/adminhtml/di.xml

 <?xml version="1.0"?> <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">     <preference for="Magento\Sales\Controller\Adminhtml\Order\Index"                  type="A2bizz\Order\Controller\Adminhtml\Order\Index" /> </config> 

if anyone can help me on what I am doing wrong. Thanks

Magento 2.2.5 Tax is not working

Magento 2.2.5 version tax is not calculating, It always show 0(zero) in cart page and checkout page.

I have been lot of search but not luck, please anyone help to fix this issue.

or

How i can alter tax amount?

Note: Tax class already assigned to product, Tax rule already in admin so please except any other solution.

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upgrade from magento 2.2.5 to 2.3 error Front controller reached 100 router match iterations Issue

As I upgraded my magento from 2.2.5 to 2.3 all works fine but when trying to access the website an iteration error appear saying: Front controller reached 100 router match iterations Issue. after searching for solutions online and all fails except that someone say something about old cached data is corrupted so I remove var/cache then clean and flush cache but the error still appears. I solved the problem by disabling cache for configuration so the cache status now is like this: Current status: config: 0 layout: 1 block_html: 1 collections: 1 reflection: 1 db_ddl: 1 compiled_config: 1 eav: 1 customer_notification: 1 config_integration: 1 config_integration_api: 1 full_page: 1 config_webservice: 1 translate: 1 vertex: 0 I think this is a temporary and not a professional solution, anyone may help me figure it out and solve the problem of config cache?