Updated Drupal to 8.6. This goes with the following updates because it's possible...
[yaffs-website] / vendor / symfony / http-foundation / Exception /
drwxr-xr-x   ..
-rw-r--r-- 527 ConflictingHeadersException.php
-rw-r--r-- 484 RequestExceptionInterface.php
-rw-r--r-- 529 SuspiciousOperationException.php