I've been using K-Meleon for quite some time now.
(since version 1.5.4)

When I upgraded to version 75.1, my bookmarked favicons
disappeared when I cleared the HISTORY data.

I experimented several times to ensure that it was HISTORY
and not CACHE, COOKIES, etc.

It looks as though favicons are stored in the
"places.sqlite" file.

And clicking either...

Tools>Privacy>Clear Data>Clear History
or
Tools>Privacy>Clear Data>Clear All
or
Tools>Privacy>Clear Data>Clear Automatically...
(and putting checkmarks in the History selections)

it ERASES everything in the "moz_favicons" table
that's within the "places.sqlite" file.

Is this a Gecko problem or K-Meleon problem?

If it's a Gecko problem (and can not be fixed) ...
my suggestion is to stored favicons like Google Chrome.

Here is an excerpt from an exported bookmark file
that Chrome created...


"https://translate.google.com/"; ADD_DATE="1440284532" ICON="data:image/png;base64,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">Google Translate
{note: html link coding is not allowed in the forum, so I removed that part}

As you can see... Chrome apparently converts ALL favicons to
a PNG format and stores it in a bookamrk file.
(so that they are univerisally acceptable and always available?)

If it's a K-Meleon problem...
maybe there's a way to clear everything from "places.sqlite"
EXCEPT the "moz_favicons" table?
Or... maybe... store favicons like the example above (from Chrome)
in the bookmark file?

T.I.A.,
BigD

Preferences panel > Cache > store favicons on iconcache.dat.

[Edit>Preferences>Network/Performance>Cache]

Putting a checkmark in
"Cache website icons on disk"
does absolutely nothing.

In version 75.1, it doesn't even create
the "infamous" IconCache.dat file.
And I do mean... infamous, because it's
always been "buggy" in the past.
(hence the reason for it's elimination)

Then it is what I initially posted and then I deleted, because in 75.0 works, that I remember to read that there were some bugs and Dorian decided to take the straight route and used the places.sqlite database.

There is no way to only remove some items from places.sqlite database (that I know of) if you don't do it manually and even doing this manually, there are loads of crossed references between places.sqlite tables, so I don't recommend to do it or History would become broken soon or later.

Ok, I'm about ready to give up on K-Meleon.

I tried Comodo IceDragon and it seems to be
way more stable than K-Meleon.

(Comodo IceDragon uses Gecko)
(Comodo Dragon uses WebKit)

LOL... it took a little trial and error,
but I finally got it to install and run
on Windows XP SP3 (my Win7 hard drive crashed).
Sidenote: Getting back to Win7 isn't real high
on my priority list right now.

What I mean by trial and error is...
I downloaded the latest version, v52.0.0.4,
because they said it would run on my system.
Wrong!!! It wouldn't install.

So I searched the web for a reason. The first answer
I came across said... "It's for newer Windows O.S.s".
And they suggested getting an older version from
filepuma.com, but didn't say "which" older version.

So I downloaded 4 older versions and tried each one,
sequentially, until it wouldn't install again.
(v45.0.0.5, v47.0.0.2, v48.0.0.1, v49.0.0.0)

Version 48.0.0.1 is the one that worked, even though
I got two error message during installation.
(just click "Ok" on both, it doesn't hurt anything)
Best guessing v49.0.0.0 (and above) are for Windows 7
and newer.

I admit... Icedragon is slow to start but damn...
it's good (even installs and runs Firefox addons)!

Which turned out to be a good thing because I imported
my bookmark file K-Meleon. First thing I noticed was
that NONE of the bookmarks had favicons. And I thought
"wow... this is going to take a long time to visit close
to two hundred website to get the favicons". Somehow...
I lucked out. While searching Firefox addons... I came
across an addon that gets ALL your bookmark favicons
in a relatively short amount of time. It opens a window
and (I assuming) grabs the source code for each bookmark,
then extract the favicon location and stores the favicon
somewhere. Clearing the HISTORY does not erases them from
your bookmark menu.

It impressed me so much that I wondered if it could
do the same for K-Meleon. But alas... I can't get it
work in K-Meleon (I can install it, but that's all).

The addon is called...
FavIcon Reloader up to FF 48 only
(favicon_reloader-0.8-fx.xpi)
There are a couple older versions of this addon
on the web but not even the oldest one works.

If someone with experience with Firefox addons
could get this to work in K-Meleon... I'd stick
with K-Meleon, because it's the lowest memory hog
of all the web browsers available.