Permissions problem

I work on Linux Mint with XAMPP. If I set the folders assets and protected/runtime to 777 the application works well. However, I read that 777 it’s no good, so I changed to 775. After setting the permissions to 775 the application throws this error: “protected/runtime” is not valid. Please make sure it is a directory writable by the Web server process.". I tried to chown the whole application but it didn’t work. Concretely, I tried:

chown -R myself.myself myapplication

chown -R myself.nogroup myapplication

chown -R myself.www-data myapplication

chown -R root.root myapplication

chown -R www-data.www-data myapplication

What should I do?