Hello,

In any chance you use Domain Access module, you should include the $conf part of the Cache module "BEFORE" the include './sites/all/modules/domain/settings.inc'; line. Otherwise cache.inc (or other incs) will not be included during bootstrap and Cache will not function.

In fact Domain Access states that its include should be at the bottom of settings.php, but can be overlooked very easily.

As "Add the following lines to your settings.php:" is rather arbitrary and Domain Access is becoming a de facto standard, this may also be noticed in the Cache documentation BTW.

Tx.