Microsoft Publisher cannot save the file
When things are not working for you and you cannot save the file as PDF when using Publisher in Windows 11/10, try toggling between your default printer and another print device. The method works with both, large publisher docs as well as single-page publisher docs. If you are running Microsoft Publisher, close it and exit. Next, go to Windows Settings and choose Devices. Next, select Printers and Scanners.
Here, look for Let Windows manage my default printer option. When found, uncheck the box marked against it. Now, choose a device under Printers & scanners that isn’t your default printer. For example, click on Fax or Microsoft Print to PDF.
Click the Manage button and then click Set as default on the next page. Now, select your printer under Printers & scanners > Manage > Set as default. Start Publisher and try to save the file as a PDF or XPS again. The error message should not appear again. Related read: Problem exporting files to PDF when using Office 365 apps. This should help.