I upgraded my server from php 5.3 to php 5.5 based on this link. I disabled the apc.so in php.ini, disabled apc module.
Drupal 7 multi-site. /home/default/public_html is the root folder for /home/domain_1/public_html, /home/domain_2/public_html, /home/domain_3/public_html, /home/domain_4/public_html
three of these domains work as usual; visitors links all work and admin can log in and administer the three websites
the fourth site reports an error: visitors cannot see the site - the WOD is really Fatal error: Call to undefined function apc_delete() in /home/default/public_html/sites/all/modules/apc/drupal_apc_cache.inc on line 289
I cleared bootstrap cache and cleared the variable but to no effect. drush cc all, drush rr, and drush cron core did not improve this situation.
What else should I look for? Any other suggestions?