The admin.php?add-ons/install-upgrade page has stopped working for me. I am used to installing add-ons by unzipping the zip file contents on my server and then copying the files from the zip to the right server root locations on the server. Then I give the admin form the xml file to use. (Option 3). This has stopped working. Now when I provide the xml file and click 'Install or Upgrade' the page returns immediately and nothing apparently happens. I don't see any output in the php-fpm error log. I could use some help debugging this one.