The problem was that all my web applications ran normally on localhost, but on server the Greek characters (or any other no-english characters) displayed with problems.
The problem was that all my web applications ran normally on localhost, but on server the Greek characters (or any other no-english characters) displayed with problems.
So, you have installed a brand new Yii 2 app (basic) or (advanced). Here are a few tips for Apache web server users to get things running more secure and better with your yii2 app.