I was having a problem with my cache plugin (W3TC) creating folders with a different ownership configuration than the rest of my WordPress installation. It caused 500 Internal Server Errors for the posts being served up by the cache.
So, after much research, and yet still not being able to figure out how to get the folders created by the cache plugin to have the same configuration as the parent folders, I changed the entire installation to have the same ownership configuration as the folders W3TC was creating. That solved the 500 errors problem.
However, now I can't manipulate files via FTP, as my FTP login requires the folder configuration I had before, in order for it to have permission to change anything.
I had the folders in the installation previously set up as ftplogin:www-data (where ftplogin was the username I log in with via FTP). I had to change it to www-data:www-data.
On the server, www-data is part of the ftplogin group, and vice-versa, ftplogin is part of the www-data group. So, I don't see why it's not compatible.
Since I can no longer manipulate files via FTP, I have to do everything by logging into the server itself. It's a pain, and I wish I could figure out how to make it all harmonize. I've searched this problem extensively online, and can't find any solution.
Any help would be appreciated. Thank you!