Hii, I don't have the add new button.How to install a new theme?
Themes are just sub-folders in
wp-content/themes, when you upload a theme in a zip file to the themes page, it just unzips the file into that folder. If it's a valid theme then it shows up on that page.
If for whatever reason this functionality is disabled, or write access isn't possible, that option won't present itself in the user interface, but I would recommend using the manual process instead
Never ran through such problem but I can suggest you to do the following:
If you are a linux user:
$cd path_to_your_wordpress_site/wp-content/ ls -lah $sudo chmod -R 755 themes
Here h flag to ls command will show you all the ownerships and permissions related to the file. If it didn't help either
go to the root directory of the web server:
sudo chown -R www-data:www-data your_wordpress_site_folder
above command is for ubuntu
$sudo chown -R apache:apache your_wordpress_site_folder
I hope it helps.
Why does this happen?
It usually happens, if you enable
Softaculous Apps Installer> WordPress> Enable Multisite (WPMU),
In this case, Wordpress creates 'Network Admin' alongside 'Admin' for using WPMU. Which allows you to upload the theme from 'Network Admin' only.
What if I wanna use the option?
You can simply go to their official website WPMU and learn how to use the features in details.