Was this immediately after updating from Firefox 19 to Firefox 20, or any other update that comes to mind (e.g., extensions, plugins, graphics driver, printer drivers)?

If this only occurs on one or a few sites, could you give some sample URLs?

Does this problem appear in print preview as well? Does it matter if you change the scaling from Shrink to Fit to a specific percentage?

I think this may have started with an update to Firefox 20. The black squares print out on all websites I visit that have pictures, most recently on Craigslist when I printed out a page of a vehicle I was considering purchasing.

The only add-on I have is Forecast Fox.

I tried printing using a specific percentage but still got the black squares. It's very baffling...

I know this sounds random for simple JPEGs, but could you try disabling Firefox's use of hardware acceleration for graphics? Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches.

You usually need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

orange Firefox button (or Tools menu) > Options > Advanced

On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"

If you restart Firefox, is there any improvement?

Could you also try Firefox's Safe Mode? That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled

In the dialog, click "Start in Safe Mode" (not Reset)

Safe mode does not automatically disable plugins. I think it's unlikely a plugin is rendering the images (usually if you right-click content hosted by a plugin you get a proprietary context menu). If you want to rule those out as well, you can disable them here:

orange Firefox button (or Tools menu) > Add-ons > Plugins category

Any difference?

I tried all your suggestions and unfortunately I'm getting the black squares printed instead of pictures/graphics.

Are you able to print images to other printers or PDF printer drivers?

I think it's possible that some component of the upgrade did not install correctly. It may be worth trying a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox.

You might want to back up your settings folder first, just in case: Back up and restore information in Firefox profiles.

Then please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Firefox from https://www.mozilla.org/firefox/fx/#desktop and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which by default is located here: C:\Program Files (x86)\Mozilla Firefox
4. Reinstall Firefox using your fresh installer file.

If you're not up for that or prefer to wait for a second opinion, a great add-on you could use as a temporary workaround (or for the long haul) is: Print pages to Pdf. By default, it uses the screen appearance rather that the print-optimized page to create the PDF, but there is a checkbox for that now (somewhere; it has many options).

I also tried uninstalling and reinstalling Firefox but that didn't help either. HOWEVER, I was able to resolve my issue by updating my printer's driver (my printer is an HP CP1215 Color LaserJet that's 2 years old). I also had to go to the printer properties in Control Panel and adjust the print processor setting to HP1215 PrintProc, whereas before it was on ZIMFPRINT.

I tried printing web pages with photos from Craigslist and lo and behold, there are actual pictures instead of black boxes! I'm still baffled why I was able to print pictures on the other browsers before. But anyway, my problem is fixed and I thank you for all your assistance. :-)

I also experienced the same problem. Switching the print processor also worked for me.

I had the same problem today with a CP1217. Went to Devices and Printers, Preferences, Advanced, Print Processor, and changed it from ZIMFPRINT to HP Color Laserjet. It works now.