loadClassCache causes issues in PHP 7 when a plugin makes use of the new RedirectGenerationEvent and a middleware that sets headers such as cookies. This is deprecated in Symfony 3.3 anyway.

Author: alanhartless

app/AppKernel.php

@@ -110,6 +110,14 @@ public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQ
             $this->boot();
         }
 
+        /*
+         * If we've already sent the response headers, and we have a session
+         * set in the request, set that as the session in the container.
+         */
+        if (headers_sent() && $request->getSession()) {
+            $this->getContainer()->set('session', $request->getSession());
+        }
+
         // Check for an an active db connection and die with error if unable to connect
         if (!defined('MAUTIC_INSTALLER')) {
             $db = $this->getContainer()->get('database_connection');

index.php

@@ -29,6 +29,9 @@
 \Mautic\CoreBundle\ErrorHandler\ErrorHandler::register('prod');
 
 $kernel = new AppKernel('prod', false);
-$kernel->loadClassCache();
+
+if (version_compare(PHP_VERSION, '7.0.0', '<')) {
+    $kernel->loadClassCache();
+}
 
 Stack\run((new MiddlewareBuilder('prod'))->resolve($kernel));

index_dev.php

@@ -29,6 +29,5 @@
 \Mautic\CoreBundle\ErrorHandler\ErrorHandler::register('dev');
 
 $kernel = new AppKernel('dev', true);
-$kernel->loadClassCache();
 
 Stack\run((new MiddlewareBuilder('dev'))->resolve($kernel));