Error message

• Notice: unserialize(): Error at offset 40 of 438 bytes in variable_initialize() (line 1174 of /var/www/drupal-7.50/includes/bootstrap.inc).
• Notice: unserialize(): Error at offset 35 of 36 bytes in variable_initialize() (line 1174 of /var/www/drupal-7.50/includes/bootstrap.inc).
• Notice: unserialize(): Error at offset 35 of 36 bytes in variable_initialize() (line 1174 of /var/www/drupal-7.50/includes/bootstrap.inc).