I'm unable to remove a file from a node. When I do, I get a browser pop-up with lots of HTML code inside of it. In the Network inspection, it looks like the post request is getting a redirection to the full node view. I can't find anything in the system log, watchdog, or Apache error log. The Apache access log shows the redirection, as well.
How can I figure out why it's doing this? I'm using Drupal 7.50 and jQuery 1.4. I'm logged in as the administrator, so it shouldn't be a permission issue.
Update: Providing the response text. There is no body, it's just headers.
: 127.0.0.1 - - [28/Jul/2016:10:49:25 -0400] "POST /file/ajax/field_thumbnail_image/und/0/form-qyfvjM-oQHvPrEy9cTIcajUEjqNlyhOhn4E-hqIu-iM HTTP/1.1" 302 -
HTTP/1.1 302 Moved Temporarily Date: Thu, 28 Jul 2016 15:54:25 GMT Server: Apache/2.4.17 (Unix) OpenSSL/1.0.1h mod_fcgid/2.3.9 X-Powered-By: PHP/5.6.19 Expires: Sun, 19 Nov 1978 05:00:00 GMT Cache-Control: no-cache, must-revalidate X-Content-Type-Options: nosniff Location: http://staging.example.com.dd:8083/whitepapers/video-content-delivery-display-critical Content-Length: 0 Keep-Alive: timeout=5, max=99 Connection: Keep-Alive Content-Type: text/html; charset=UTF-8