The QuickBooks unable to locate PDF viewer error is an issue that many users face while trying to view or print PDFs from the QBDT app. It is generally caused by a damaged or corrupted QBPrint.qbp file or Adobe Reader not being set up as your default PDF viewer. This can lead to you not being able to print payroll tax forms, paychecks, and other important documents, ultimately hampering your workflow and business progress. To fix it, open the QB Tool Hub, go to the Program Problems tab, and run the QuickBooks PDF & Print Repair Tool.