My Joomla is 3.9.4. When I tried to make some global configuration change in the backend, I got this error:
Could not write to the configuration file.
I looked at the file system, configuration.php has the right owner and is set to
0644, and I can make changes to it via FTP.
I then tried setting the permission to
0777, it is writable; then I tried
0664 and it is also good.
Only when I set it to
0644 do I get the above error. I've never encountered this kind of problem before. I suspect it is something wrong with my server(I host the website on a VPS on linode), but I couldn't figure out.
What could possibly be wrong?
UPDATE I found some more clues. This website was duplicated from another server where the website ran well. When I look both site's FPA, I found that on the problematic server, the permission section is like
I don't understand how come one is writable whereas the other is not while both permissions are 0755.