Okay, can you provide the steps to replicate the issue? What are you trying to print? Is it a doc, pdf, or from a site?

I get the error message when I try to print to my printer or to PDF from all websites viewed with Firefox, such as my email account, Insurance or banking sites. So if I am looking at my email and I want to print to a PDF to save the email, I get the "An error occurred while printing". The same happens if I try to print to my printer. I can run a test print okay from any website, just not a document. Thank you in advance for any help you might give me. I really prefer to use Firefox and not Chrome which I have started using.

Reset Firefox printer setting

Several printer issues can be resolved by resetting Firefox's printer settings:

   Type about:config in the address bar and press Enter.
   A warning page may appear. Click Accept the Risk and Continue to continue to the about:config page.
   In the Search field, type print_printer.
   Click the Delete Fx71aboutconfig-DeleteButton button to the right of the print_printer preference.
   Click the Firefox menu Fx57Menu and select Exit. 

When you start Firefox again, try printing the page that you had problems with previously.

From: https://support.mozilla.org/en-US/kb/fix-printing-problems-firefox

I just followed your instructions and I still have the problem. Like I said in my original post, have tried updating to the latest version of FF 84.0.1 (64-bit), doing a Refresh, following the Support suggestions for printer problems, editing my profile etc. To no end. But I understand there are steps that should be followed to diagnose a problem.

I will assume you're running some type of virus or security software. Can you close that software and then open Firefox and try to print again.

I tried that in very beginning, In fact, I uninstalled all my virus software in the beginning and still had the had the problem. But I just exited out of my current virus software and still have the problem. This started just after the Firefox updates in November 2020. I have thought about trying to install an older version of Firefox to see what that would do.

Yes, you should Install an old version to see what happens.

I downloaded FF version 82, I then uninstalled version 84, I restarted my computer and installed FF ver 82. I created a new profile, then logged into my Mozilla account. A Refresh Firefox bar was visible along the bottom of my screen, but I did not refresh. I tried to print and got the same error message. I then click on the refresh link along the bottom and got a Mozilla screen indicated I now had the latest version of Firefox. I check the "about Firefox" which indicated I was running version 84 and not 82. I am now wondering if this problem is some how tied to my Mozilla account? That when I log into my account, something is moved from the cloud to my computer causing the printing error? I am just throwing out ideas now.

What is your printer paper size set to? Just pulling things from research... Can you also try turning off hardware acceleration?

printer paper size is set to letter for both printer and pdf. I am old, so I am still running Windows 7, and I apparently can only disabling hardware acceleration from my computer’s registry, and I do not feel comfortable doing that.

Not from the registry, but in browser settings. see screenshot

Mine was set for "Use recommended performance settings". So I unchecked and unchecked "Use hardware acceleration when available". Then exited out of options, and closed and restarted FF, but still got the printing error.

Have you tried in Safe Mode? I'm also running Win7, let me switch to it and print a pdf.

When do you get the error? Is right after you click print or after the print preview? I'm able to print pdfs in Firefox from Win 7 and Linux. It would say record your screen showing the process and post the error on YouTube. I use OBS to record my screen. Also, check to see if there are any errors in the Windows Logs using eventvwr.msc after getting the error.

I get two error messages depending if I select pdf or to my printer. When I click on Print, I automatically get a print preview screen. Then when I select print pdf or print to printer, I get a "Print Preview Error" that reads. An error occurred while printing. When I close that screen, another popup screen appears with a "Creating Adobe PDF": An error occurred while printing. If I choose to print to my printer, I only get the Print Preview error. I will see what happens when I start my computer in SAFE MODE.

Try this. Create another windows account Login and turn off all virus and security software Open Firefox, but do not log into the Firefox account and try the process again.