User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:97.0) Gecko/20100101 Firefox/97.0

Steps to reproduce:

Hello, in the Privacy and Security panel it is possible to force Firefox to delete cookie and site data upon closing the program, but it is not possible to make it clear the cache.

Actual results:

Since Cookies, cache and site data are grouped together in the "Clear data" dialog (in which you can choose to clean cookies + site data, cache, or both), I expect that the option "Delete cookies and site data when Firefox is closed" would clean all (that is cookies, site data AND cache).

The cleaning cache procedure, on the other side, is rather difficult to find and the option is located elsewhere in the interface.

https://support.mozilla.org/en-US/kb/how-clear-firefox-cache#w_automatically-clear-the-cache

It is not so clear, in a "common user" perspective, what is the difference between "site data" and "cache": in fact, a user complained in the Italian support forum about Firefox not being able to clear cache on close.

Expected results:

I see some possible ways to handle this.

1. Make the option also force to clean the cache when Firefox is closed

2. Create another option at the end of the section.

"Delete cache when Firefox is closed"

3. Specify that the option doesn't involve the cleaning of the cache, for example

"Delete cookies and site data (not the cache) when Firefox is closed"

Hope I was clear...

Thanks for filing a bug!

I agree that it would be more intuitive if the "Delete cookies and site data when Firefox is closed" checkbox also cleared caches. I'll put this bug in our backlog.

As part of Bug 1681493 we're changing the underlying mechanism of the checkbox. It will no longer be a standalone feature but use the "Clear history when Nightly closes" functionality under "Use custom settings for history".

The "Delete cookies and site data when Firefox is closed" checkbox actually does clear caches, but only for sites that have cookies set or occupy some disk space.
We could extend the PrincipalsCollector to look through the caches as well.

(In reply to hpeuckmann@mozilla.com from comment #2)

The "Delete cookies and site data when Firefox is closed" checkbox actually does clear caches, but only for sites that have cookies set or occupy some disk space.

Hi, I've simply found that, upon marking that very checkbox, the entries in about:cache?storage=disk are not deleted between restarts.
Doesn't this mean that some disk space is actually occupied by the cache?

(In reply to Underpass from comment #3)

(In reply to hpeuckmann@mozilla.com from comment #2)

The "Delete cookies and site data when Firefox is closed" checkbox actually does clear caches, but only for sites that have cookies set or occupy some disk space.

Hi, I've simply found that, upon marking that very checkbox, the entries in about:cache?storage=disk are not deleted between restarts.
Doesn't this mean that some disk space is actually occupied by the cache?

Hey, that is right, the cache needs to be persisted between sessions so it occupies disk space. But the implementation behind "clear cookies and site data" only clears caches for sites that ether use quota storage or cookie storage. I was referring to the quota storage when I was mentioning disk space, sorry for that I should have been more precise. If you want to clear your browser cache on shutdown for now you can use the "clear history when Firefox closes" option with "cache" ticked (under the "use custom settings for history" menu) that should do the job.

Ok, now I know, but hence the little inconsistency of the option.
Thanks