diff --git a/admin/tool/task/lib.php b/admin/tool/task/lib.php
index 56cd18310dd..64d99754e8e 100644
--- a/admin/tool/task/lib.php
+++ b/admin/tool/task/lib.php
@@ -45,5 +45,6 @@ function tool_task_status_checks() : array {
  * @param string $eol End of line character
  */
 function tool_task_mtrace_wrapper(string $message, string $eol): void {
-    echo s($message . $eol);
+    $message = s($message);
+    echo $message . $eol;
 }
diff --git a/admin/tool/task/run_adhoctasks.php b/admin/tool/task/run_adhoctasks.php
index d665e40278d..1b45035d893 100644
--- a/admin/tool/task/run_adhoctasks.php
+++ b/admin/tool/task/run_adhoctasks.php
@@ -111,6 +111,7 @@ require_sesskey();
 \core\session\manager::write_close();
 
 // Prepare to handle output via mtrace.
+require('lib.php');
 $CFG->mtrace_wrapper = 'tool_task_mtrace_wrapper';
 
 // Run the specified tasks.
diff --git a/admin/tool/task/schedule_task.php b/admin/tool/task/schedule_task.php
index ecaaf7efde0..bdd02bfb693 100644
--- a/admin/tool/task/schedule_task.php
+++ b/admin/tool/task/schedule_task.php
@@ -89,6 +89,7 @@ echo $OUTPUT->select_element_for_append();
 
 // Prepare to handle output via mtrace.
 echo html_writer::start_tag('pre', ['style' => 'color: #fff; background: #333; padding: 1em; min-height: 24lh']);
+require('lib.php');
 $CFG->mtrace_wrapper = 'tool_task_mtrace_wrapper';
 
 // Run the specified task (this will output an error if it doesn't exist).
diff --git a/lib/classes/task/manager.php b/lib/classes/task/manager.php
index 58bb2609556..90ea9450205 100644
--- a/lib/classes/task/manager.php
+++ b/lib/classes/task/manager.php
@@ -1516,12 +1516,40 @@ class manager {
             $command = "{$phpbinary} {$scriptpath} {$taskarg}";
 
             // Execute it.
-            passthru($command);
+            self::passthru_via_mtrace($command);
         }
 
         return true;
     }
 
+    /**
+     * This behaves similar to passthru but filters every line via
+     * the mtrace function so it can be post processed.
+     *
+     * @param string $command to run
+     * @return void
+     */
+    public static function passthru_via_mtrace(string $command) {
+        $descriptorspec = [
+            0 => ['pipe', 'r'], // STDIN.
+            1 => ['pipe', 'w'], // STDOUT.
+            2 => ['pipe', 'w'], // STDERR.
+        ];
+        flush();
+        $process = proc_open($command, $descriptorspec, $pipes, realpath('./'), []);
+        if (is_resource($process)) {
+            while ($s = fgets($pipes[1])) {
+                mtrace($s, '');
+                flush();
+            }
+        }
+
+        fclose($pipes[0]);
+        fclose($pipes[1]);
+        fclose($pipes[2]);
+        proc_close($process);
+    }
+
     /**
      * Executes an ad hoc task from web invocation using PHP CLI.
      *
@@ -1586,7 +1614,7 @@ class manager {
         }
 
         // Execute it.
-        passthru($command);
+        self::passthru_via_mtrace($command);
     }
 
     /**