How to fix 'Some files are not writable by WordPress' error, website cannot be changed by admin
Solution 1:
Apart from permissions you have to change the Owner of the Files to the web server user ( most cases, especially those using apache www-data ) .
The command to do that is the below
$ sudo chown -R www-data:www-data /path/to/wordpress/
the usual path of a website on a ubuntu server is /var/www/domain.com/ but of course that depends !
Wish you the best!
Solution 2:
change all files and folders permission as follow:
enter your public_html folder and execute this two commands
find . -type d -exec chmod 0755 {} \;
find . -type f -exec chmod 0644 {} \;