Let me help you print your checks in QuickBooks, @wrightr1.

I know how frustrating it is to get an unexpected error when trying to do something very important. To make up with you here in the Community, let me provide you some troubleshooting steps that will fix your printing issues.

If you find the right margin of your invoice is being cut off during printing, adjust your printing setup and alignment in QuickBooks Online. If that doesn't fix the issue, check your settings in Preview. Here's how:
 

1. Click Sales or Invoicing.
2. Select an invoice to print.
3. Once it's opened, choose Print or Preview.
4. Select Print or press Command-P on the print preview screen,
5. Click Show Details to adjust print settings.
6. Go to the Orientation section and make sure the scale is set to 100%.
7. Select Paper Handling in the drop-down menu and unchecked the Scale to fit paper size.
8. Set the border to None.

If you have third-party PDF plug-ins installed (including Adobe's own plug-ins), you'll need to remove them from Safari. This allows Safari's own internal PDF viewer to take over as the browser's default PDF handler. Let's follow these steps:
 

1. Quit Safari and open a new Finder window. Then, click the Go menu and select Go To Folder.
2. Enter the following in the field: /Library/Internet Plug-Ins/.
3. If there are plugins named PDF Browser Plugin.plugin, AdobePDFViewerNPAPI.plugin, or AdobePDFPDE.plugin, move them to the trash or somewhere else on your system. You may need to enter your password to authorize the removal.
4. Re-open Safari and sign in to QuickBooks Online.
5. Try to print your document.

In addition, printing issues may be resolved by installing an updated printer driver or by using a generic Postscript driver that comes with OS X.

You can also refresh QuickBooks Online App if the issue persist. Simply click Help, and then Reset App Data. 

Feel free to go back to this thread if you need anything else. QuickBooks Community is always open to provide additional assistance.