I just finished migrating my server, and was unable to write/make updates on my Wordpress server. I ended up following a guide and ran these permission changes: sudo usermod -aG www-data $USER sudo chown -R www-data:www-data /var/www sudo chmod -R 774 /var/www This fixed the write issues, but I am no longer able to access the ISPConfig Login page. Any help is super appreciated! Thank you!!
The commands you executed completely messed up all website permissions and the permissions of the ISPConfig system. Do you still have the system where you migrated from? If yes, reinstall the new system and do the migration again and under no circumstances, run these commands. If you had write issues before, then you either missed enabling the suexec module in apache or you missed enabling the suexec checkbox in the website settings or you had chosen a wrong PHP mode, for CMS systems like Wordpress which write to the website directory, PHP mode must be php-fpm or php-fcgi and all files and folders inside the web directory of a site must be owned by the web user and client group of that site, they are NOT owned by www-data.