I have the following error on my site which is now not loading. I have a database backup but if I can avoid too many problems I would appreciate it.

Warning: Concrete5_Library_Loader::require_once(/home/hawkwell/public_html/hafc/updates/concrete5.6.0.2/concrete/models/json.php) [concrete5-library-loader.require-once]: failed to open stream: No such file or directory in /home/hawkwell/public_html/hafc/updates/concrete5.6.0.2/concrete/core/libraries/loader.php on line 40

Fatal error: Concrete5_Library_Loader::require_once() [function.require]: Failed opening required '/home/hawkwell/public_html/hafc/updates/concrete5.6.0.2/concrete/models/json.php' (include_path='/home/hawkwell/public_html/hafc/libraries/3rdparty:/home/hawkwell/public_html/hafc/updates/concrete5.6.0.2/concrete/libraries/3rdparty:.:/usr/lib/php:/usr/local/lib/php') in /home/hawkwell/public_html/hafc/updates/concrete5.6.0.2/concrete/core/libraries/loader.php on line 40