https://support.mozilla.org/en-US/kb/update-firefox-latest-version 46.0.1

Location of the cache files. Windows: *C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profiles\<profile>\ Mac: ~/Library/Caches/Firefox/Profiles/ Linux:~/.cache/mozilla/firefox/

Close Firefox. Open your file browser to the above, and remove the folder.

Thank you FredMcD that seems to have worked.

Glad to help. Safe Surfing.

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily.

Thank you for contacting Mozilla Support.

My enthusiasm towards the problem being solved was premature.Two clicks worked when the cache had about 10Mb in it, but when fuller (160Mb) it still took about 10-12 clicks on the 'Clear Now' button in Preferences/Advanced/Cached Web Content to fully empty it.

See if this works better; Empty Cache Button {web link} Cache clearing made easy. One click.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

I installed the add-on in your above link and the cache now empties with one click. Thanks.

Note that the "Clear Now" on the Options/Preferences page starts clearing the cache in the background. This page doesn't get updated more than once to shows the progress of the clearing, so you get the impression that nothing happens. You can refresh the about:preferences page via F5 or the reload button to see if the clearing has finished already.

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily.

Thank you for contacting Mozilla Support.

FredMcD,

I have to wonder why a person needs to install an add-on to clear cache. A couple of us have been writing about this since v45, if not earlier.

I am on my second or third install of v47 and instead of being slow deleting, I cannot get down past 1.2MB. I've never had that much remain.

If this running in the background works for the majority of people as massive numbers of us are not complaining, then what am I supposed to do?

The reason for clearing - or thinking that I need to clear cache - is some websites are so poorly designed, that they will load very slowly. Then there are other websites where I can't attribute poor design or construction and I'm basically annoyed with having anything but a smooth experience on the internet - every day, for years.

As an aside or an extension, there are two things that jump out after I download a new version. I get a boatload of freezes (FF "not responding") or I get a poorly clearing cache. A boatload means not occasionally, but each time I alternate between two websites, I'm dodging freezes and self-corrections. At a minimum after the automatic download, I am cleanly installing new versions a minimum of three additional times. Why does the same version behave so differently?

Is the Mozilla Maintenance Service program possibly contributing to these issues? It's the only noticeable thing (to me) that's different with downloads, but I don't remember when you first offered the service.

Thank you.

CiaoBella1 Please go to the top of any support.mozilla.org web page and use the Ask A Question link; https://support.mozilla.org/en-US/questions/new This will let us look at your system details. No Personal Information Is Collected.

Done.

Thank you.