Error message

• Warning: unlink(/var/www/html/sites/default/tmp/update-cache-d2678d83/memcache-7.x-1.5.tar.gz): Permission denied in drupal_unlink() (line 2353 of /var/www/html/includes/file.inc).
• Warning: rmdir(/var/www/html/sites/default/tmp/update-extraction-d2678d83/memcache): Permission denied in drupal_rmdir() (line 2517 of /var/www/html/includes/file.inc).
• Warning: Illegal offset type in isset or empty in VariableRealmDefaultController->getStore() (line 267 of /var/www/html/sites/all/modules/variable/variable_realm/variable_realm.class.inc).
• Warning: Illegal offset type in VariableRealmDefaultController->setStore() (line 294 of /var/www/html/sites/all/modules/variable/variable_realm/variable_realm.class.inc).
• Warning: Illegal offset type in isset or empty in variable_store() (line 15 of /var/www/html/sites/all/modules/variable/variable_store/variable_store.module).
• Recoverable fatal error: Object of class stdClass could not be converted to string in _variable_store_load() (line 103 of /var/www/html/sites/all/modules/variable/variable_store/variable_store.module).