How to solve 404 page not found error when SEO urls used or SEO url 404 error?

1. check in admin panel whether you are activated Use SEO URL's to Yes or not.

 Goto admin panel system->settings-> Server

Then check  Use SEO URL's to Yes.

How to hide the errorrs,warnings,notice and all kinds of things in Opencart?

We can hide the all kinds of issues by just following the below steps in opencart.

First of all search for the below line in index.php.

1.set_error_handler('error_handler');

2. And comment the line.