I have always in private mode enabled. Why is there a small web cache stored each time I open firefox?
Basically I have Never Remember History enabled, and each time I open FF there's data in 'Cookies and Site Data'. Under 'Cookies and Site Data' it will say there's a bit of data (in the photo is says 16Kb, which is pretty typical). If I look under 'manage cookies and site data' there will be nothing there. Sometimes the cookies or cache or whatever is bigger if the last time I used that profile I was watching videos, at most it will be a couple Mb's maybe. If I wipe it out, it will go to 0Kb, and then for the rest of the profile session, even if I have a bazillion tabs open, it will say 0, but then there's always a cache there the next time I start that profile.
What is it? Why is there always a small amount of data in the 'Cookies and Site Data' section each time I restart a profile?
I'm currently running version 68.2.0esr on Debian Linux version 5.3.0-1-amd64. I use uBlock Origin 1.23.0 and uMatrix 1.4.0 and Canvasblocker 0.5.14. I have web history turned off ('Never Remember History'), trackers blocked, cookies enabled w/ third party disabled, auto search engine update turned on, Do Not Track enabled, 'Delete cookies and site data when Firefox is closed' enabled by default (b/c history is off). I might have changed a few tiny things in about:config but nothing I remember. Any other system info I can look up in need be.
I'm sorry if this is a repost, I've tried searching for a bit.
All Replies (5)
Firefox saves all your tabs and when you reopen the browser those tabs come back with the session cookies for those pages. To avoid this you have to close all your tabs then close the browser. Otherwise you'd have to turn off “Restore previous pession” in “Options”.
This could be any number of things. When you first open Firefox, it connects to a few services, some of which may produce cached data. In addition, your extensions that you have installed also may make some initial connections.
For example, a content blocking extension may connect to a server to check for an updated list of things to block. Firefox itself may connect to the updating service or load the extension blocklist or connect to the safe browsing service, all of which could make cache files.
Seeing a small amount of cached data when you first open Firefox is normal. It's not stuff left over from your previous session, it's stuff that's created on startup.
Hope this answers your question.
Firefox needs some cookies for internal usage like retrieving data and checking for updates and for phishing protection, so maybe that is what you see.
cor-el said
Firefox needs some cookies for internal usage like retrieving data and checking for updates and for phishing protection, so maybe that is what you see.
All of these responses are kinda along the lines of what I was thinking, except for one thing: Like I mentioned, I've noticed that if I go to some websites that have a lot of media content, then the next time I open that FF profile I see a couple of megabytes instead of a few kilobytes. I think that this is something different than all of these otherwise quite plausible explanations. Hopefully I will get some time to look through the profile contents and maybe I can track it down and reply again. It maybe could be uMatrix having cached a lot of different content blocks. as Wesley Branton suggested.
Do you have the SiteSecurityServiceState.txt file in the profile folder?