I understand the process of telling MacOS and the Finder what application should handle what file type, but that didn't change my issue. Let me give the step by step;
in QuickBooks for Mac desktop edition:
1) open the payroll module, in my case with the "add payroll" button in the main tool bar, and log in.
2) click the "Payday" tab.
3) look to the right of the navigation bar under the tabs and click "Paycheck List".
4) check the box next to any one or multiple paychecks.
5) click the "View & Print" button.
it's at this point that the payroll module throws the generated PDF file specifically to Adobe Reader 9
no matter what the Finder or MacOS in general has been told to use to handle PDF files.
So here's where I'm going to escalate this to a bug and say Quickbooks Mac desktop version is HARD LINKED to Adobe Reader, and there's little guarantee that Adobe Reader 9 will continue to run on MacOS, and indeed has various problems simply operating under MacOS Mojave (let alone Catalina...is it even 64bit?)
I archived the earlier version of Adobe Reader (and any other earlier version I had) and have only the current Acrobat product installed to handle PDF files. In any other instance, mac applications all happily hand off any generated PDF files to my one and only PDF handling product, the current release of Acrobat in the Adobe Creative Suite.
So now in following the step-by-step above, when one clicks "View & Print" in step 5, Quickbooks (again - I'm doing this in the PAYROLL module, in case THAT is where in the code this hard-link has been written in...), one is presented with the error modal dialog I've attached in an image. Any subsequent attempts to view and print after that first error present a second error dialog box indicating "there is still a file being generated...wait for that file to complete or close and refresh the module".
So there you have it. TL:dr - the payroll module in QuickBooks for Mac desktop edition is unable to generate various reports or paystubs without passing thru an old version of Adobe Reader, and appears to be hard-linked to a specific "Adobe Reader" application title rather than respecting the Finder's or the operating system's tagged application for handling PDF files. This needs to be corrected.
Happy bug fixing!
PS - I may be wrong, but I believe the version of Acrobat Reader (version 9.x) that's hard linked is 32bit application code and will not run at all if one updates to Catalina. Another reason to UNlink this hard link and figure out how to make the payroll module respect the OS's tagged handler for PDF files.
