Unable to load ajax requested pages

Question

My apologies, first of all, if this comes across vague. I'm experiencing an issue that I can barely understand and thus find it hard to frame it as a clearly coherent question.

Problem:

When loading a page, content inside of a JQueryUI tabs fails. Looking at Chrome Developer Tools, the AJAX requests are returning 500 Internal Server Errors.

Typically, I'd look at the server's httpd error log (this is a CentOS system), but nothing shows as anything warning or higher. I changed the error logging to debug and captured this.

[Fri Jun 10 08:26:57.748313 2022] [authz_core:debug] [pid 15452:tid 139940536825600] mod_authz_core.c(820): [client ::1:58584] AH01626: authorization result of Require all granted: granted, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748324 2022] [authz_core:debug] [pid 15452:tid 139940536825600] mod_authz_core.c(820): [client ::1:58584] AH01626: authorization result of <RequireAny>: granted, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748338 2022] [proxy:debug] [pid 15452:tid 139940536825600] mod_proxy.c(1254): [client ::1:58584] AH01143: Running scheme unix handler (attempt 0), referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748341 2022] [proxy_ajp:debug] [pid 15452:tid 139940536825600] mod_proxy_ajp.c(743): [client ::1:58584] AH00894: declining URL fcgi://localhost/var/www/html/nexgen/app/tabs/endpoints.php, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748344 2022] [proxy_fcgi:debug] [pid 15452:tid 139940536825600] mod_proxy_fcgi.c(1021): [client ::1:58584] AH01076: url: fcgi://localhost/var/www/html/nexgen/app/tabs/endpoints.php proxyname: (null) proxyport: 0, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748346 2022] [proxy_fcgi:debug] [pid 15452:tid 139940536825600] mod_proxy_fcgi.c(1028): [client ::1:58584] AH01078: serving URL fcgi://localhost/var/www/html/nexgen/app/tabs/endpoints.php, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748351 2022] [proxy:debug] [pid 15452:tid 139940536825600] proxy_util.c(2315): AH00942: FCGI: has acquired connection for (*)
[Fri Jun 10 08:26:57.748355 2022] [proxy:debug] [pid 15452:tid 139940536825600] proxy_util.c(2368): [client ::1:58584] AH00944: connecting fcgi://localhost/var/www/html/nexgen/app/tabs/endpoints.php to localhost:8000, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748357 2022] [proxy:debug] [pid 15452:tid 139940536825600] proxy_util.c(2405): [client ::1:58584] AH02545: fcgi: has determined UDS as /run/php-fpm/www.sock, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748399 2022] [proxy:debug] [pid 15452:tid 139940536825600] proxy_util.c(2577): [client ::1:58584] AH00947: connected /var/www/html/nexgen/app/tabs/endpoints.php to httpd-UDS:0, referer: http://localhost:2222/nexgen/index.html
[Fri Jun 10 08:26:57.748410 2022] [proxy:debug] [pid 15452:tid 139940536825600] proxy_util.c(2948): AH02823: FCGI: connection established with Unix domain socket /run/php-fpm/www.sock (*)
[Fri Jun 10 08:26:57.748746 2022] [proxy:debug] [pid 15452:tid 139940536825600] proxy_util.c(2330): AH00943: FCGI: has released connection for (*)

I've checked my conf files to make sure that I've granted access to the directory. The error logs seems to show that those are being granted. The problem seems to be with mod_proxy_ajp. However, this shouldn't be a problem since I'm not using AJAX to get content over a reverse proxy.

I've checked file permissions, setting everything to 777 (for testing purposes) with no success. I've "flattened" out the directory structure and put all of the tabbed files into the same top directory with the index.html with no success.

The initial index.html loads without an issue. I created a test.php file to see if security exceptions were a problem. The test.php loaded successfully, so there's something going on with the AJAX.

The JQuery code that governs this is below:

$("#tabs").tabs({
        beforeLoad: function (event, ui) {
          ui.jqXHR.fail(function () {
            ui.panel.html(
              "Couldn't load this tab. We'll try to fix this as soon as possible. " +
              "If this wouldn't be a demo.");
          });
        },
        load: function (event, ui) {
          $("#filterTerm").off("keyup").on("keyup", function () {
            var value = $(this).val().toLowerCase();
            $("#dataTable tr").filter(function () {
              $(this).toggle($(this).text().toLowerCase().indexOf(value) > -1)
            });
          });
          $("#muteSelect").selectmenu({
            change: function (event, ui) {

              var muteValue = $(this).val().toLowerCase();

              switch (muteValue) {

                case "unmuted":
                  muteValue = "on";

                  break;
                case "muted":
                  muteValue = "off"

                  break;

                default:
                  muteValue = "";
              }

              var letter = $(this).val();
              if (muteValue === 'Both') {
                $('tr').show();
              } else {

                $('tr').each(function (rowIdx, tr) {

                  $(this).find('td').find('button').each(function (idx, td) {
                    var check = $(this).attr("current");
                    if (idx === 0 || idx === 1) {
                      if (check && check.indexOf(muteValue) == 0) {
                        $(tr).show();
                      } else {
                        $(tr).hide();
                      }
                    }
                  });

                });
              }


            }
          });

          jqAttach();

        }
      });

Thank you for your help and I admit this question could be better, but I'm struggling with concepts and very unfamiliar territory. Please let me know what information I can provide or razzies if I missed the obvious answer.

Thanks.