Firefox HTML Document (.html) icon changed to black

Is there a way to change it back to white?

I would say NO.

In my case, when I create URL shortcut on my desktop to the website, the look of Firefox HTML document icon will depend on if the website using favorite icon. If website is using favorite icon I get white shortcut with the site's small icon in the middle.
If website doesn't use favorite icon I get black shortcut with Firefox logo inside shortcut.

Did it happen to all your Firefox URL shortcuts?

https://en.wikipedia.org/wiki/Favicon

MozartMan said:

I would say NO.

In my case, when I create URL shortcut on my desktop to the website, the look of Firefox HTML document icon will depend on if the website using favorite icon. If website is using favorite icon I get white shortcut with the site's small icon in the middle.
If website doesn't use favorite icon I get black shortcut with Firefox logo inside shortcut.

https://en.wikipedia.org/wiki/Favicon

Url shortcut? It's a saved page. File > Save page as > Test.html

When you save page to your desktop or folder on you hard drive Firefox will created folder in the same location with the same name as your saved HTML page. In that folder Firefox will save a bunch of files, like CSS files, images, JS (JavaScript) files in order for your page to display properly when open that saved page in the browser. BUT, Firefox doesn't save favorite icon file (either image or actual ICO file). That's why you get black icon with Firefox logo inside.

Did it happen after you updated Firefox, or is it just happened some day?

MozartMan said:

When you save page to your desktop or folder on you hard drive Firefox will created folder in the same location with the same name as your saved HTML page. In that folder Firefox will save a bunch of files, like CSS files, images, JS (JavaScript) files in order for your page to display properly when open that saved page in the browser. BUT, Firefox doesn't save favorite icon file (either image or actual ICO file). That's why you get black icon with Firefox logo inside.

Did it happen after you updated Firefox, or is it just happened some day?

Updated to ESR 60. The icons are the same except they're black instead of white. They looked like this but without the shortcut arrow.

Another conspiracy theory may be is that Mozilla developers changed icon color from white to black.

I have Firefox 62 stable release and if I save page on the desktop my icons have black background color.
If I created "Internet shortcut" the color of FF icon depends if website is using favorite icon.

MozartMan said:

Another conspiracy theory may be is that Mozilla developers changed icon color from white to black.

I have Firefox 62 stable release and if I save page on the desktop my icons have black background color.
If I created "Internet shortcut" the color of FF icon depends if website is using favorite icon.

Yeah, I figured it was something like that. Hopefully they revert it, but I'm not going to hold my breath.

Here is some info about Firefox ESR:

All Firefox channels have received updates: Firefox Stable to version 62.0, Firefox Beta to version 63.0, Firefox Nightly to version 64.0, and Firefox ESR to Firefox ESR 60.2.

The new version of Firefox ESR is a milestone release, at least for Firefox ESR users who are still using Firefox ESR 52.x as the version is no longer supported and Firefox 60.x does not support legacy extensions anymore.

More info here: https://www.ghacks.net/2018/09/04/fi...e-information/