The thumbnails on the about:newtab page are generated from the cache, so if the page is not in the cache or otherwise can't be rendered as a PNG image then you will get an empty box.

Pages that send a no-store or no-cache header aren't cached and thus Firefox doesn't generate a thumbnail.

• https://developer.mozilla.org/en/Tools/Web_Console

Thanks cor-el, nice to get an informed explanation. I posted elsewhere and no one seemed to have a clue. Not deleting cache should fix this.

You're welcome

This seems to only provide directions to open the web console but doesn't tell me how to use it to fix the problem of new tab not having thumbnails - my new tab goes to a bing search page instead of the page of images.

I only mentioned the Web Console as a tool to inspect the HTTP response headers and not as a way to fix things.
If pages aren't in the cache then Firefox won't generate a new image if it isn't in the thumbnails cache.

I'm trying to restore new tab having thumbnails. Don't know what I did to make this go away. Tried going in to Web Console but I have no idea what to do from that point on.

Does the New Tab page (about:newtab) still show the nine (3x3) squares that can hold the links and thumbnails?

See also this article about the New Tab page (about:newtab):

• https://support.mozilla.org/kb/new-tab-page-show-hide-and-customize-top-sites

Try to use the SearchReset extension to reset some preferences to the default values.

• https://addons.mozilla.org/firefox/addon/searchreset/

Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons).

@Michael2020 and anyone having similar problem: I think this happens when you install programs on your computer. Some of these installations changes things in your browser. Sometimes they change your homepage and sometimes they change the new tab page setup. Strangely enough, if you get this "bing" search page when you open a new tab, look at the bottom left corner of the page, there should be 2 links there...one says "Reset" and one says "Contact". I clicked on reset, and when i opened a new tab, the thumbnails setup was back. So if you see this at the bottom of your page, give it a shot, it worked for me, probably will for you as well.

I used the SearchReset extention above and it solved my problem. Thanks much, you can't imagine how glad I am to get my problem solvedf!!!