У вашего броузера проблема в совместимости с HTML5
Easy configure frontend & backend url in yii 2. This tutorial show how to configure frontend url default 'frontend/web' can be hiding and backend url change to administrator using .htaccess files. So, we can acces our website using base url. e.g http://domain.com and backend http://domain.com/administrator.
Configure Frontend & Backend Url in Yii2 (Part 2) : https://www.youtube.com/watch?v=lfv-E2qcWnU
The step is easy:
1. Create .htaccess file in root directory
2. Create .htaccess file in frontend directory
3. Copy .htaccess file in frontend directory to backend directory
4. add 'homeUrl' and 'baseUrl' in backend config file.
This tutorial is based from http://www.hafidmukhlasin.com/2014/09/28/yii2-pengaturan-website-url-frontend-backend/