Drupal 7.54 DATE_RFC7231 already defined After moving my Drupal site to a new host, I got the following error in the error logs.


  [error] 8707#0: *1 FastCGI sent in stderr: "PHP message: PHP Notice:  Constant DATE_RFC7231 already defined in /ext/vhosts/public/includes/bootstrap.inc on line 258


How can I fix it?

My site currently says "The website encountered an unexpected error. Please try again later"

My setup is as follows:


Debian 8
PHP 7.0.21
MySQL 5.6
Drupal 7.54
Are you certain you're running PHP 5 and not a version of PHP 7? I've only ever seen that error when running PHP 7, and it was due to DATE_RFC7231 already defined in PHP 7.0.19 and 7.1.5.

Either way, the patches in that issue were committed and released with 7.55, so it might be worth trying a core update before anything else.