When you open Administrator Backend, you see Warning Internet Explorer.
This warning can occur when you restore web from server to localhost on XAMPP, or after upgrade/update version Joomla 4. Some files *.css.gz and *.js.gz may be not load.
You need stop .htaccess, by rename .htaccess to htaccess.txt
Then, reopen browser go to Administrator, refresh webpage.Remember rename htaccess.txt to .htaccess when you finished it.
Xiroweb
Author
Dustin Dzung
Dustin Dzung with 15 years of experience in using and developing websites with Joomla!, from the first version of Mambo to Joomla! 1.0 and up to the present Joomla! 5.x.