What is happening with W3TC sometimes?

It always add to the files’ extensions “.old”

I think disabling, deleting (including all files using ftp) and reintalling W3TC can solve the problem, but it’s the second time when it’s happening

clear reinstalling helped

I think clicking “Empty All Caches” in wp-admin caused that problem

I also doubt about all these buttons “purge the page”, “empty all caches” and so on. Some of them don’t work (“purge the page”) or cause problems (“Empty All Caches”)

I usally use ftp or file manager to remove cache manually when i update, create something

This is done under the expiration and garbage collection settings in page caching its meant to update your pages automatically by recaching them (incase of changes) and to delete the expired pages.

i know what is needed for
but it was disabled (any auto purge) and i didn’t create, edit any pages, but it was still removing every cached folders, creating new (when someone open specific page), and again removing it (cycle)